MQE: fix panic in rate or increase over native histograms with changing schema

[charleskorn]

What this PR does

This PR fixes a panic in MQE when rate or increase is used over a range of native histograms that change schema multiple times.

Which issue(s) this PR fixes or relates to

(none)

Checklist

• Tests updated.
• [n/a] Documentation added.
• CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX].
• [n/a] about-versioning.md updated with experimental features.

[jhesketh]

Nice find. In checking why Prometheus' engine didn't suffer this I think we can optimise where we are copying the schema. Granted it's probably not a frequent operation.

[jhesketh]

I think we can avoid doing this so often. If we track the min schema, we only need to copy delta to the min schema once it has finished accumulating points (and /maybe/ on line 108 before the add (I'm not as sure about there, would need to check).

[charleskorn]

Very possibly, but I'd like to keep the scope of this PR as small as possible, so I'll do that in a follow-up PR.

[charleskorn]

#9531

[grafanabot]

The backport to r308 failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new branch
git switch --create backport-9518-to-r308 origin/r308
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x caa2fb9b60ae460a84323c638f9c4875a2a12797
# Push it to GitHub
git push --set-upstream origin backport-9518-to-r308
git switch main
# Remove the local backport branch
git branch -D backport-9518-to-r308

Then, create a pull request where the base branch is r308 and the compare/head branch is backport-9518-to-r308.

[grafanabot]

The backport to r309 failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new branch
git switch --create backport-9518-to-r309 origin/r309
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x caa2fb9b60ae460a84323c638f9c4875a2a12797
# Push it to GitHub
git push --set-upstream origin backport-9518-to-r309
git switch main
# Remove the local backport branch
git branch -D backport-9518-to-r309

Then, create a pull request where the base branch is r309 and the compare/head branch is backport-9518-to-r309.

[grafanabot]

The backport to r310 failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new branch
git switch --create backport-9518-to-r310 origin/r310
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x caa2fb9b60ae460a84323c638f9c4875a2a12797
# Push it to GitHub
git push --set-upstream origin backport-9518-to-r310
git switch main
# Remove the local backport branch
git branch -D backport-9518-to-r310

Then, create a pull request where the base branch is r310 and the compare/head branch is backport-9518-to-r310.