Run current-run E2E app cleanup in CI

[alfonso-noriega]

WHY are these changes introduced?

E2E tests can leave real Dev Dashboard apps behind when teardown is skipped or fails. The previous workflow did not run a post-test app cleanup step, so leftovers accumulated in the shared E2E organization.

Stacked on #7926: the cleanup pattern relies on the run-aware app names introduced by the parent PR.

WHAT is this pull request doing?

Adds an always() cleanup step after the E2E test command that computes the same compact run token as the E2E app-name helper and runs:

RUN_TOKEN=$(node -e "process.stdout.write(BigInt(process.env.GITHUB_RUN_ID).toString(36))")
pnpm --filter e2e exec tsx scripts/cleanup-apps.ts --pattern "r${RUN_TOKEN}a${GITHUB_RUN_ATTEMPT}"

The step targets only apps created by the current GitHub Actions run attempt and is marked continue-on-error: true so cleanup flakiness does not hide the original E2E result.

How to test your changes?

• git diff --check
• Inspect .github/workflows/tests-pr.yml and confirm the cleanup step is after Run E2E tests with if: ${{ always() }}.
• In CI, verify the Cleanup current-run E2E apps step runs for E2E shards even if the test command fails.

Post-release steps

None.

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've considered possible documentation changes
• I've considered analytics changes to measure impact
• The change is not user-facing, so no changeset is needed