bk: honour the bk-pr-bot feature to manage non-mergeable PRs

[v1v]

What is the problem this PR solves?

Remove unnecessary post-command hooks and honour the bk-pr-bot features

How to test this PR locally

In the CI after being merged

Design Checklist

• I have ensured my design is stateless and will work when multiple fleet-server instances are behind a load balancer.
• I have or intend to scale test my changes, ensuring it will work reliably with 100K+ agents connected.
• I have included fail safe mechanisms to limit the load on fleet-server: rate limiting, circuit breakers, caching, load shedding, etc.

Checklist

• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in ./changelog/fragments using the changelog tool

Related issues

similarly solved at elastic/beats#38305

[prodsecmachine]

🎉 Snyk checks have passed. No issues have been found so far.

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[elastic-sonarqube]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarQube