Update mimir-prometheus to incl MemPostings improvements

[colega]

What this PR does

Updates mimir-promteheus to bring changes from:

• MemPostings.Delete(): reduce locking/unlocking prometheus/prometheus#13286
• MemPostings.PostingsForLabelMatching(): don't hold the mutex while matching prometheus/prometheus#14286

Which issue(s) this PR fixes or relates to

Fixes an internal issue.

Checklist

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

[gotjosh]

LGTM

[grafanabot]

The backport to r292 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-8327-to-r292 origin/r292
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x 6cc0bf7bcb7c6909501a5ec5958ec3cdc0f29dd6
# Push it to GitHub
git push --set-upstream origin backport-8327-to-r292
git switch main
# Remove the local backport branch
git branch -D backport-8327-to-r292

Then, create a pull request where the base branch is r292 and the compare/head branch is backport-8327-to-r292.

[grafanabot]

The backport to r291 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-8327-to-r291 origin/r291
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x 6cc0bf7bcb7c6909501a5ec5958ec3cdc0f29dd6
# Push it to GitHub
git push --set-upstream origin backport-8327-to-r291
git switch main
# Remove the local backport branch
git branch -D backport-8327-to-r291

Then, create a pull request where the base branch is r291 and the compare/head branch is backport-8327-to-r291.

[grafanabot]

The backport to r293 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-8327-to-r293 origin/r293
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x 6cc0bf7bcb7c6909501a5ec5958ec3cdc0f29dd6
# Push it to GitHub
git push --set-upstream origin backport-8327-to-r293
git switch main
# Remove the local backport branch
git branch -D backport-8327-to-r293

Then, create a pull request where the base branch is r293 and the compare/head branch is backport-8327-to-r293.

[grafanabot]

The backport to r294 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-8327-to-r294 origin/r294
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x 6cc0bf7bcb7c6909501a5ec5958ec3cdc0f29dd6
# Push it to GitHub
git push --set-upstream origin backport-8327-to-r294
git switch main
# Remove the local backport branch
git branch -D backport-8327-to-r294

Then, create a pull request where the base branch is r294 and the compare/head branch is backport-8327-to-r294.

[colega]

I will not merge this backports, I'll create mimir-prometheus branches instead, as they're likely starting from different versions.