Fix memory issues when computing retrieval metrics with high-valued indices

[adaliaramon]

What does this PR do?

Fixes #3290. No update to the docs or new test are required, as far as I can tell. Tests are passing.

Before submitting

• Was this discussed/agreed 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

Memory usage is now independent of the values of the indices.

Did you have fun?

Make sure you had fun coding 🙃

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📚 Documentation preview 📚: https://torchmetrics--3291.org.readthedocs.build/en/3291/

[justusschock]

Very Nice @adaliaramon ! Do you have comparison numbers in memory usage?

[adaliaramon]

Not really but just from the example in the issue it comes down from 67 GB to basically nothing

[codecov]

Codecov Report

❌ Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 37%. Comparing base (fd967c0) to head (d1d0a12).

❌ Your project check has failed because the head coverage (37%) is below the target coverage (95%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #3291    +/-   ##
=======================================
- Coverage      37%     37%    -1%     
=======================================
  Files         364     349    -15     
  Lines       20096   19899   -197     
=======================================
- Hits         7520    7326   -194     
+ Misses      12576   12573     -3     

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