CI - Skip Internal Tests and Unreal Tests on external PRs (#3522)

# Description of Changes

These tests fail on external PRs, but not for any real reasons - just
because GH secrets are missing. "Skipped" is more informative than
"failed".

# API and ABI breaking changes

None.

# Expected complexity level and risk

1

# Testing

None, but I just copied the logic from the unity testsuite.

---------

Co-authored-by: Zeke Foppa <bfops@users.noreply.github.com>

Author: bfops

.github/workflows/ci.yml

@@ -277,6 +277,8 @@ jobs:
     # This can't go on e.g. ubuntu-latest because that runner runs out of disk space. ChatGPT suggested that the general solution tends to be to use
     # a custom runner.
     runs-on: spacetimedb-runner
+    # Skip if this is an external contribution. GitHub secrets will be empty, so the step would fail anyway.
+    if: ${{ github.event_name != 'pull_request' || !github.event.pull_request.head.repo.fork }}
     container:
       image: ghcr.io/epicgames/unreal-engine:dev-5.6
       credentials:

.github/workflows/csharp-test.yml

@@ -173,4 +173,4 @@ jobs:
           UNITY_SERIAL: ${{ secrets.UNITY_SERIAL }}
         # Skip if this is an external contribution.
         # The license secrets will be empty, so the step would fail anyway.
-        if: ${{ !github.event.pull_request.head.repo.fork }}
+        if: ${{ github.event_name != 'pull_request' || !github.event.pull_request.head.repo.fork }}

.github/workflows/internal-tests.yml

@@ -17,6 +17,8 @@ concurrency:
 
 jobs:
   run-tests:
+    # Skip if this is an external contribution. GitHub secrets will be empty, so the step would fail anyway.
+    if: ${{ github.event_name != 'pull_request' || !github.event.pull_request.head.repo.fork }}
     runs-on: ubuntu-latest
     steps:
       - name: Print current ref and sha