Rmt cleanup old metadata

[paragjain0910]

Description

This task is for cleaning up old metadata files after repository updates in the CDN.

https://trello.com/c/SznwZfr3/3662-l3-regression-rmt-doesnt-clean-up-metadata

How to test ( locally )

1) Enable a repository using the command:  ` rmt-cli repos enable <repo-id>`
2) Run the mirror command:  ` rmt-cli mirror`
3) Rename any metadata file in the repodata directory (e.g., rmt/public/repo/SUSE/Products/SLE-Product-SLES/15-SP6/ppc64le/product/repodata).
4) Run the mirror command again: `   rmt-cli mirror`

Check whether it will remove the renamed metadata file from the repodata directory and download the updated one from the CDN.

Change Type

Please select the correct option.

• [* ] Bug Fix (a non-breaking change which fixes an issue)
• New Feature (a non-breaking change which adds new functionality)
• Documentation Update (a change which only updates documentation)

[felixsch]

lgtm 👍

How I reviewed this pull request:

• Checked for changes I want to suggest
• Ran the branch and mirrored repository:
  • Renamed a file to simulate updated metadata
  • Checked the files get cleaned
  • Remirrored and checked again

As always, if you think I missed something I should test, please let me know!🚀