Disable Focal on Harmonic

[azeey]

Summary

Harmonic only supports Jammy so removing Focal CI.

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[codecov]

Codecov Report

Merging #868 (412efc8) into main (cab8b84) will increase coverage by 0.01%.
The diff coverage is n/a.

❗ Current head 412efc8 differs from pull request most recent head da01d5b. Consider uploading reports for the commit da01d5b to get more accurate results

@@            Coverage Diff             @@
##             main     #868      +/-   ##
==========================================
+ Coverage   75.02%   75.03%   +0.01%     
==========================================
  Files         183      176       -7     
  Lines       16311    16830     +519     
==========================================
+ Hits        12237    12629     +392     
- Misses       4074     4201     +127     

see 161 files with indirect coverage changes