temp: run nightly-testcontainers on this PR + add actions-timeline

Adds a scoped pull_request trigger so this workflow runs on this PR
itself, to get real GHA runner timing before deciding whether/how to
adopt this pattern more broadly. Also adds the actions-timeline job
(same pattern as superset-python-presto-hive.yml) to visualize per-step
duration.

Revert the pull_request trigger before merge -- it's here to measure
cost, not to become a permanent merge-blocking check.

.github/workflows/nightly-testcontainers.yml

@@ -16,6 +16,12 @@ on:
   schedule:
     - cron: "0 5 * * *"
   workflow_dispatch: {}
+  # TEMPORARY: pull_request lets this run on this PR itself to get real GHA
+  # timing before merge. Revert before merge -- see apache/superset#43502.
+  pull_request:
+    paths:
+      - ".github/workflows/nightly-testcontainers.yml"
+      - "tests/testcontainers/**"
 
 concurrency:
   group: ${{ github.workflow }}
@@ -48,3 +54,12 @@ jobs:
           name: junit-results-testcontainers
           path: test-results/
           retention-days: 7
+
+  actions-timeline:
+    needs: [testcontainers]
+    if: always()
+    runs-on: ubuntu-26.04
+    permissions:
+      actions: read
+    steps:
+      - uses: Kesin11/actions-timeline@57fc93f20c6da7fbc14063c6d24a2a5627c799ad # v3.2.0