[mergify] close stalled PRs with the bump automation

[v1v]

What

1. Delete open PRs older than 3 days on a daily basis if they are created by the apmmachine
2. Auto-merge PRs if they are created by the apmmachine are part of the automated bump process

Why

• Obsoleted bumps are not needed.
• Some Automated PRs don't change the docker-compose.yml files anymore.

[mergify]

This pull request does not have a backport label. Could you fix it @v1v? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-v./d./d./d is the label to automatically backport to the 7./d branch. /d is the digit
  NOTE: backport-skip has been added to this pull request.

[v1v]

For instance:

#1848 matched the previous behaviour of chjanges in the docker-compose.yml but #1849 somehow is only touching one file

This author filtering will allow the merge for the above-mentioned PRs.

[v1v]

Unrelated, but commented, so this will ensure PRs older than 2 days will be affected

[elasticmachine]

💚 Build Succeeded

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Build stats

• Start Time: 2021-12-01T12:51:06.929+0000

• Duration: 4 min 3 sec

• Commit: ffa1475

Test stats 🧪

Test	Results
Failed	0
Passed	19
Skipped	0
Total	19

💚 Flaky test report

Tests succeeded.

🤖 GitHub comments

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