Don't report expected lazy import exclusion failures to GitHub

The "Verify excluded tests still need exclusion" step expects each
excluded test to fail; unset GITHUB_STEP_SUMMARY so those failures
aren't annotated or added to the job summary.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: cmaloney

.github/workflows/reusable-test-lazy-imports-all.yml

@@ -64,6 +64,8 @@ jobs:
     - name: Verify excluded tests still need exclusion
       run: |
         set -euo pipefail
+        # Failures are expected here, don't report them to the job summary
+        unset GITHUB_STEP_SUMMARY
         unexpected_passes=()
         while IFS= read -r test_name; do
           [ -n "$test_name" ] || continue