fix(logql): A renamed label should use ParsedLabel category to take precendence (backport k224)

[loki-gh-app]

Backport 82fb2f0 from #14515

---

What this PR does / why we need it:

Renaming labels using label_format dst=src is broken on main. Destination label does not appear in the resulting label set if the source is a stream label. This is because we don't append the labels from add[StreamLabel] list to the resulting buffer, this looks like a conscious choice to not pollute StreamLabels.

I felt the correct fix here is to correctly tag the renamed label as a ParsedLabel. This also makes sure the new label supersedes any structured metadata if present.

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
  • Note that Promtail is considered to be feature complete, and future development for logs collection will be in Grafana Alloy. As such, feat PRs are unlikely to be accepted unless a case can be made for the feature actually being a bug fix to existing behavior.
• Changes that require user attention or interaction to upgrade are documented in docs/sources/setup/upgrade/_index.md
• If the change is deprecating or removing a configuration option, update the deprecated-config.yaml and deleted-config.yaml files respectively in the tools/deprecated-config-checker directory. Example PR

[ashwanthgoli]

lgtm