Add main build validation for release workflow (aws-observability#443)

*Issue #, if available:*

*Description of changes:*
This PR modifies the release build workflow to wait for the main build
workflow in the same branch to complete successfully. before proceeding
with the release. If the latest main build run has status `queued` or
`in_progress`, or has completed without the conclusion `success`, the
workflow exits early.

Tested this logic in personal fork with dummy workflows.
failed release workflow example 1 (main build in progress):
https://github.com/ezhang6811/aws-otel-python-instrumentation/actions/runs/17478717524/job/49644636222
failed release workflow example 2 (main build failed):
https://github.com/ezhang6811/aws-otel-python-instrumentation/actions/runs/17478713160/job/49644619601
successful release workflow example:
https://github.com/ezhang6811/aws-otel-python-instrumentation/actions/runs/17478731487

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choice.

Author: ezhang6811

.github/workflows/release-build.yml

@@ -28,6 +28,24 @@ jobs:
       - name: Checkout Repo @ SHA - ${{ github.sha }}
         uses: actions/checkout@v4
 
+      - name: Check main build status
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          WORKFLOW_ID=$(gh api repos/${{ github.repository }}/actions/workflows --jq '.workflows[] | select(.name=="Python Instrumentation Main Build") | .id')
+          LATEST_RUN=$(gh api repos/${{ github.repository }}/actions/workflows/$WORKFLOW_ID/runs --jq '[.workflow_runs[] | select(.head_branch=="${{ github.ref_name }}")] | sort_by(.created_at) | .[-1] | {conclusion, status}')
+          STATUS=$(echo "$LATEST_RUN" | jq -r '.status')
+          CONCLUSION=$(echo "$LATEST_RUN" | jq -r '.conclusion')
+          
+          if [ "$STATUS" = "in_progress" ] || [ "$STATUS" = "queued" ]; then
+            echo "Main build is still running (status: $STATUS). Cannot proceed with release."
+            exit 1
+          elif [ "$CONCLUSION" != "success" ]; then
+            echo "Latest main build on branch ${{ github.ref_name }} conclusion: $CONCLUSION"
+            exit 1
+          fi
+          echo "Main build succeeded, proceeding with release"
+
       - name: Build Wheel and Image Files
         uses: ./.github/actions/artifacts_build
         with: