If PG 2pc commit fails, don't call CommitBundleResources.

[rynewang]

Placement group manager crashes in this time order:

1. sent PREPARE to all nodes;
2. received PREPARE reply from all nodes;
3. one node dead
4. send COMMIT to all nodes
5. for the dead node, the manager knows it's dead, but still called CommitBundleResources
6. CommitBundleResources asserts the node always exist and check failed.

This PR removed the call to CommitBundleResources in step 5.

Also, it fixed some unit tests that never worked (always pass). Added a test case specifically for this code path.

Fixes #43371.

[jjyao]

LG. Let's add tests.

[rynewang]

Tests added.