Code cleaning after classification refactor 1/n

[SkafteNicki]

What does this PR do?

Cleaning after the classification refactor.
This PR cleans metrics that were directly removed, move to other domain or included in some other metric.

Before submitting

• Was this discussed/approved via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure to update the docs?
• Did you write any new necessary tests?

PR review

Anyone in the community is free to review the PR once the tests have passed.
If we didn't discuss your PR in Github issues there's a high chance it will not be merged.

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[codecov]

Codecov Report

Merging #1251 (c35620f) into master (eacfd2f) will decrease coverage by 36%.
The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff            @@
##           master   #1251     +/-   ##
========================================
- Coverage      86%     49%    -36%     
========================================
  Files         195     190      -5     
  Lines       11378   11108    -270     
========================================
- Hits         9754    5480   -4274     
- Misses       1624    5628   +4004     

[Borda]

not sure why make docs complains about types :(

[SkafteNicki]

not sure why make docs complains about types :(

Docs were failing because I had removed this file https://github.com/Lightning-AI/metrics/blob/eacfd2fcd4521fb3c69bcb53e5b1be9117c8a163/docs/source/pages/classification.rst and not all the links to that file.
Should be fixed now.

The info in that file is old and in the two follow up PRs I will redo the docstrings of all the old metrics so it matches the new interface.