bug: flaky tests in github runner

[apoorvsadana]

The stop_indexer and failed_stop_indexer tests are flaky. They work sometimes and fail at other times on the github runner. They always work locally and even doing an ssh into the self hosted runner and running the tests didn't reproduce it. By adding logs to the error, it looks like the apibara sink closes with channel closed

Here's an unsusscesful run with logs - https://github.com/Astraly-Labs/indexer-service/actions/runs/6584796812/job/17890044364

The issue is that we want to stop the indexer but because it failed to run, the stop indexer API call also results in FailedStopping (couldn't stop because nothing was running).