feat: Configurable number of rotated log files

[doominator42]

Description

Since there is the variable LOGROTATE_INTERVAL, it would be useful to be able to adjust the number of files kept by logrotate, so I added LOGROTATE_COUNT.

Type of change

• Improvement (non-breaking change that does improve existing functionality)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (README.md or the documentation under docs/)
• If necessary, I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have added information about changes made in this PR to CHANGELOG.md

[doominator42]

I was not sure about the format of the CHANGELOG, should I add a section Added with my change or add it under Updates?

[casperklein]

Added is good for new features 👍

[doominator42]

I added my change to the CHANGELOG, this PR is now ready for review.

[georglauterbach]

LGTM 👍

[github-actions]

Documentation preview for this PR is ready! 🎉

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