[CHANGE] regexp . to match \n and optimize performance

[ywwg]

This is backported from Prometheus 3.0 prometheus/prometheus#14505

Shortcut for .* matches newlines as well.
Add preamble change ^(?s:
Add test
dotAll flag por al regex
Add and fix regex tests

Co-authored-by: Mario Fernandez [email protected]

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[ywwg]

I have signed the agreement although the assistant seems to think I have not

[ywwg]

Also I can either squash the commits down or leave them separate... not sure how important it is to keep the commits in mimir-prometheus relatively close to upstream.

[56quarters]

Also I can either squash the commits down or leave them separate... not sure how important it is to keep the commits in mimir-prometheus relatively close to upstream.

If they are separate in Prometheus main or the release branch, leave them separate here. It makes it easier to apply further changes.

[pracucci]

Hold on before merging. Not sure we're ready to merge this in main. There was a discussion in the last Mimir weekly about the breaking changes being / not being merged in mimir-prometheus main. Better if you kick off a discussion in #mimir-dev first.

[ywwg]

converted to draft so nobody gets tempted to push the button

[ywwg]

(I'll start the discussion on monday, no need to do so on a friday afternoon)