ci(e2e): add job-level timeout to matrix E2E job (#404)

The matrix E2E job (api-level 29-36) had no timeout-minutes, so a wedge
hangs until GitHub's 6-hour default instead of being force-killed. The
sibling e2e-preview job already sets timeout-minutes: 35. A normal
matrix run is ~15-20 min and a retry-inclusive run ~40 min, so set
timeout-minutes: 50 to give headroom above the in-step wedge-capture
timeout (1200s) while still bounding worst-case runtime.

.github/workflows/ci.yml

@@ -397,6 +397,7 @@ jobs:
     needs: changes
     if: needs.changes.outputs.e2e_needed == 'true'
     runs-on: ubuntu-latest
+    timeout-minutes: 50
     strategy:
       fail-fast: false
       matrix: