[Core] fix flaky reference count test by cleaning up borrowed references if actor is killed before dependencies are not resolved

[rkooo567]

Why are these changes needed?

When a actor is killed before dependencies are resolved, it doesn't send the reply to the caller (there's a wrong assumption here), and the caller doesn't call proper APIs to clean up borrowed references. This PR fixes the issue by sending a reply when actor is killed before dependencies are resolved and calling FailPendingTask, which in turns clean up borrowed references.

Related issue number

Closes #48087

Checks

• I've signed off every commit(by using the -s flag, i.e., git commit -s) in this PR.
• I've run scripts/format.sh to lint the changes in this PR.
• I've included any doc changes needed for https://docs.ray.io/en/master/.
  • I've added any new APIs to the API Reference. For example, if I added a
    method in Tune, I've added it in doc/source/tune/api/ under the
    corresponding .rst file.
• I've made sure the tests are passing. Note that there might be a few flaky tests, see the recent failures at https://flakey-tests.ray.io/
• Testing Strategy
  • Unit tests
  • Release tests
  • This PR is not tested :(

[rkooo567]

cpp test fails. I will fix it tmrw