Switch to GitHub-hosted runner with OIDC authentication

- Change from gha-runner-ecr-publish to ubuntu-latest
- Add AWS OIDC authentication with role assumption
- Requires AWS_ROLE_ARN secret to be configured

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: pbasgod7

.github/workflows/build-and-push.yml

@@ -24,7 +24,10 @@ env:
 jobs:
   build-and-publish:
     name: Build and Publish Grafana Quickwit Image
-    runs-on: gha-runner-ecr-publish
+    runs-on: ubuntu-latest
+    permissions:
+      id-token: write
+      contents: read
     outputs:
       githash: ${{ steps.metadata.outputs.githash }}
       image_tag: ${{ steps.metadata.outputs.image_tag }}
@@ -35,6 +38,12 @@ jobs:
         with:
           fetch-depth: 0
 
+      - name: Configure AWS credentials
+        uses: aws-actions/configure-aws-credentials@v4
+        with:
+          role-to-assume: ${{ secrets.AWS_ROLE_ARN }}
+          aws-region: ${{ env.AWS_REGION_MGT }}
+
       - name: Generate metadata
         id: metadata
         run: |