The new Docbot spams PRs with multiple comments

[lhotari]

Describe the bug
The new Docbot (#15797) added in #16027 spams PRs with multiple comments.

To Reproduce
There's an example in #16045
https://github.com/apache/pulsar/actions/workflows/ci-documentbot.yml

Example jobs:

Logs:
https://github.com/apache/pulsar/runs/6874257583?check_suite_focus=true
https://github.com/apache/pulsar/runs/6874257484?check_suite_focus=true
https://github.com/apache/pulsar/runs/6874256005?check_suite_focus=true

Expected behavior
The docbot shouldn't spam users with the same nagging message multiple times on the same PR.

Additional context
You can find workflow runs in https://github.com/apache/pulsar/actions/workflows/ci-documentbot.yml .
The workflow has been disabled until the problem is solved.

[lhotari]

@maxsxu @Anonymitaet I have disabled the docbot until this problem has been addressed since it's also spamming users with GitHub notifications.

[lhotari]

In https://github.com/apache/pulsar/blob/master/.github/workflows/ci-documentbot.yml
there should be config to limit the concurrency so that there's one build job handling events for a single PR at a time.

Adding this to the yaml will accomplish that:

concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}

docs for concurrency: https://docs.github.com/en/actions/using-jobs/using-concurrency

[Anonymitaet]

@lhotari thanks for your guidance and resource! @maxsxu is fixing this issue and will keep you updated.