ci: reduce checkout history footprint in PR workflows (#27221)

* ci: reduce checkout history footprint in PR workflows

Optimize actions/checkout usage to avoid downloading the full repo blob
history on every PR run. The repo is large, so cloning everything just
to run tests wastes minutes of CI time per job.

- py-operator-build-test.yml: drop fetch-depth: 0 (no history needed)
- openmetadata-service-unit-tests.yml: drop fetch-depth: 0 (Sonar is
  explicitly skipped via -Dsonar.skip=true); shallow-fetch PR base ref
- airflow-apis-tests.yml, py-tests.yml, yarn-coverage.yml: add
  filter: blob:none to Sonar jobs so commits/trees remain available
  for blame while blobs are fetched lazily on demand
- ui-checkstyle.yml: add filter: blob:none to all jobs that rely on
  tj-actions/changed-files (needs commit/tree metadata, not blobs)

* ci: drop fetch-depth: 0 from jobs that don't walk history

Follow-up audit after the initial pass. Four jobs were still declaring
fetch-depth: 0 (plus filter: blob:none in two cases) without actually
needing any history beyond HEAD.

ui-checkstyle.yml
- i18n-sync: runs 'yarn i18n' then 'git status --porcelain'. git status
  compares the working tree to HEAD; no history walk. Default depth 1
  is sufficient.
- app-docs: same pattern with 'yarn generate:app-docs'.

py-sonarcloud-nightly.yml
- py-unit-tests: only uploads a coverage artifact, no Sonar invocation.
- py-integration-tests: same.
- py-combine-coverage: does run SonarSource/sonarqube-scan-action, so
  it genuinely needs the commit graph — added filter: blob:none for
  parity with the PR Sonar jobs.

* ci: remove unused 'Fetch PR base branch' step from service unit tests

Copilot review flagged that the step was using --depth=1 while the main
checkout is also shallow, which would break any merge-base operation.
On investigation, nothing downstream actually uses the base ref: the
only command that runs after the checkout is 'mvn ... -Dsonar.skip=true',
which has no git dependency. The step was preserved defensively in the
previous commit, but it's dead code — cleanest fix is to delete it.

Author: pmbrull

.github/workflows/airflow-apis-tests.yml

@@ -61,6 +61,7 @@ jobs:
       with:
         ref: ${{ github.event.pull_request.head.sha }}
         fetch-depth: 0
+        filter: blob:none
 
     - name: Set up JDK 21
       uses: actions/setup-java@v4

.github/workflows/openmetadata-service-unit-tests.yml

@@ -74,11 +74,6 @@ jobs:
         uses: actions/checkout@v4
         with:
           ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
-          fetch-depth: 0
-
-      - name: Fetch PR base branch
-        if: ${{ github.event_name == 'pull_request' }}
-        run: git fetch --no-tags origin ${{ github.event.pull_request.base.ref }}
 
       - name: Cache Maven dependencies
         uses: actions/cache@v4

.github/workflows/py-operator-build-test.yml

@@ -66,7 +66,6 @@ jobs:
         uses: actions/checkout@v4
         with:
           ref: ${{ github.event.pull_request.head.sha }}
-          fetch-depth: 0
 
       - name: Setup Openmetadata Test Environment
         uses: ./.github/actions/setup-openmetadata-test-environment

.github/workflows/py-sonarcloud-nightly.yml

@@ -49,7 +49,6 @@ jobs:
         uses: actions/checkout@v4
         with:
           ref: ${{ env.BRANCH_NAME }}
-          fetch-depth: 0
 
       - name: Setup Openmetadata Test Environment
         uses: ./.github/actions/setup-openmetadata-test-environment
@@ -110,7 +109,6 @@ jobs:
         uses: actions/checkout@v4
         with:
           ref: ${{ env.BRANCH_NAME }}
-          fetch-depth: 0
 
       - name: Setup Openmetadata Test Environment
         uses: ./.github/actions/setup-openmetadata-test-environment
@@ -154,6 +152,7 @@ jobs:
         with:
           ref: ${{ env.BRANCH_NAME }}
           fetch-depth: 0
+          filter: blob:none
 
       - name: Setup Python
         uses: actions/setup-python@v5

.github/workflows/py-tests.yml

@@ -232,6 +232,7 @@ jobs:
         with:
           ref: ${{ github.event.pull_request.head.sha }}
           fetch-depth: 0
+          filter: blob:none
 
       - name: Setup Python
         uses: actions/setup-python@v5

.github/workflows/ui-checkstyle.yml

@@ -84,6 +84,7 @@ jobs:
         with:
           ref: ${{ github.event.pull_request.head.sha }}
           fetch-depth: 0
+          filter: blob:none
 
       - uses: actions/setup-node@v4
         with:
@@ -194,6 +195,7 @@ jobs:
         with:
           ref: ${{ github.event.pull_request.head.sha }}
           fetch-depth: 0
+          filter: blob:none
 
       - uses: actions/setup-node@v4
         with:
@@ -377,7 +379,6 @@ jobs:
       - uses: actions/checkout@v4
         with:
           ref: ${{ github.event.pull_request.head.sha }}
-          fetch-depth: 0
 
       - uses: actions/setup-node@v4
         with:
@@ -461,7 +462,6 @@ jobs:
       - uses: actions/checkout@v4
         with:
           ref: ${{ github.event.pull_request.head.sha }}
-          fetch-depth: 0
 
       - uses: actions/setup-node@v4
         with:
@@ -546,6 +546,7 @@ jobs:
         with:
           ref: ${{ github.event.pull_request.head.sha }}
           fetch-depth: 0
+          filter: blob:none
 
       - uses: actions/setup-node@v4
         with:
@@ -654,6 +655,7 @@ jobs:
         with:
           ref: ${{ github.event.pull_request.head.sha }}
           fetch-depth: 0
+          filter: blob:none
 
       - uses: actions/setup-node@v4
         with:
@@ -755,6 +757,7 @@ jobs:
         with:
           ref: ${{ github.event.pull_request.head.sha }}
           fetch-depth: 0
+          filter: blob:none
 
       - uses: actions/setup-node@v4
         with:

.github/workflows/yarn-coverage.yml

@@ -48,8 +48,11 @@ jobs:
       - uses: actions/checkout@v4
         with:
           ref: ${{ github.event.pull_request.head.sha }}
-          # Disabling shallow clone is recommended for improving relevancy of reporting
+          # Disabling shallow clone is recommended for improving relevancy of reporting.
+          # Use partial clone (blob:none) to avoid downloading every blob in history —
+          # commits/trees still available for Sonar blame; blobs fetched lazily as needed.
           fetch-depth: 0
+          filter: blob:none
 
       - name: Setup Node.js
         uses: actions/setup-node@v4