Fix rate metrics type

[FlorentClarret]

What does this PR do?

Update the metadata file to declare rate metrics as rates.

Motivation

We wanted to add an extra check in the tests in the PR #12689 and it showed that the metadata.csv file was incorrect. Fixing it in a separate PR.

Additional Notes

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• PR title must be written as a CHANGELOG entry (see why)
• Files changes must correspond to the primary purpose of the PR as described in the title (small unrelated changes should have their own PR)
• PR must have changelog/ and integration/ labels attached

[codecov]

Codecov Report

Merging #12704 (d7c7a20) into master (9410e98) will increase coverage by 0.00%.
The diff coverage is 100.00%.

Flag	Coverage Δ
mcache	93.56% <100.00%> (+0.04%)	⬆️

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[FlorentClarret]

Closing the PR as this is not a bug