fix(metrics): change targetallocator ServiceAccount name

[swiatekm]

This is to avoid conflict with the operator's default. After the change, we can freely switch between the two without worrying about ownership conflicts. Helm errors if we tell it to manage a resource which already exists and is managed by the operator.

In #3515 we let the operator manage the target allocator's ServiceAccount. Then in #3539, we went back to managing it ourselves, because we needed to attach our own pull secrets to it. This results in an error when upgrading, because Helm refuses to manage a resource which is already managed by the operator, based on standard labels. Changing the name fixes this problem.

Fixes #3588. I'm also going to backport this change to v4.5 and release v4.5.2, as it currently blocks the upgrade for any user with Otel metrics enabled.

Checklist

• Changelog updated or skip changelog label added
• Template tests added for new features

[sumo-backporter]

The backport to release-v4.5 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 working tree
git worktree add .worktrees/backport-release-v4.5 release-v4.5
# Navigate to the new working tree
cd .worktrees/backport-release-v4.5
# Create a new branch
git switch --create backport-3604-to-release-v4.5
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 6581b47285f29488458e7b775d6495c059fe1a80
# Push it to GitHub
git push --set-upstream origin backport-3604-to-release-v4.5
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-release-v4.5

Then, create a pull request where the base branch is release-v4.5 and the compare/head branch is backport-3604-to-release-v4.5.