Rename time_taken to time_taken_ms - #7649

Get the unreleased section into the shape RELEASE.md asks for before the
release-1.22 cut, so operators reading the notes see the changes that affect them:

- Delete the stale duplicate of cortexproject#7375, which already shipped in 1.21.0 as cortexproject#7370.
- Re-sort into CHANGE -> FEATURE -> ENHANCEMENT -> BUGFIX.
- Correct the gRPC entry: the bump landed at v1.82.1, not v1.79.3.
- Fold follow-up PRs into the entry they belong to.
- Add three missing user-facing entries: cortexproject#7513, cortexproject#7514 and cortexproject#7559.
- Reclassify as CHANGE the entries that break existing configs or log consumers:
  the sign-key validation (cortexproject#7587), the Alertmanager per-tenant *_file rejections
  (cortexproject#7767, cortexproject#7768, now one entry) and the time_taken -> time_taken_ms rename (cortexproject#7649).
- Note the operator impact of the distroless base image (cortexproject#7637) and of the
  500 -> 499 reclassification (cortexproject#7717).

Rebased onto master, which added eight entries after this was first written.
They are curated the same way:

- Sorted into their categories: the deprecated flag removal (cortexproject#7790) and the
  max-exemplars deprecation (cortexproject#7793) under CHANGE, the X-Grafana-User query log
  (cortexproject#7799) under ENHANCEMENT, the YAML zero-value validation (cortexproject#7700) and the
  ReadPartitionedGroupInfo error handling (cortexproject#7766) under BUGFIX.
- Folded the Go toolchain bump (cortexproject#7807, cortexproject#7814) into the existing build image
  entry, which now reads 1.27.0 rather than carrying a second entry for it.
- Folded cortexproject#7745 into cortexproject#7698: both are the same wipe-on-transient-DNS-failure bug,
  cortexproject#7698 on the A record path and cortexproject#7745 on the SRV path.
- Folded cortexproject#7743 into cortexproject#7640: both are panics in the active request tracker's
  truncation of match[]/query values.

Signed-off-by: Charlie Le <charlie_le@apple.com>

Get the unreleased section into the shape RELEASE.md asks for before the
release-1.22 cut, so operators reading the notes see the changes that affect them:

- Delete the stale duplicate of cortexproject#7375, which already shipped in 1.21.0 as cortexproject#7370.
- Re-sort into CHANGE -> FEATURE -> ENHANCEMENT -> BUGFIX.
- Correct the gRPC entry: the bump landed at v1.82.1, not v1.79.3.
- Fold follow-up PRs into the entry they belong to.
- Add three missing user-facing entries: cortexproject#7513, cortexproject#7514 and cortexproject#7559.
- Reclassify as CHANGE the entries that break existing configs or log consumers:
  the sign-key validation (cortexproject#7587), the Alertmanager per-tenant *_file rejections
  (cortexproject#7767, cortexproject#7768, now one entry) and the time_taken -> time_taken_ms rename (cortexproject#7649).
- Note the operator impact of the distroless base image (cortexproject#7637) and of the
  500 -> 499 reclassification (cortexproject#7717).

Rebased onto master, which added eight entries after this was first written.
They are curated the same way:

- Sorted into their categories: the deprecated flag removal (cortexproject#7790) and the
  max-exemplars deprecation (cortexproject#7793) under CHANGE, the X-Grafana-User query log
  (cortexproject#7799) under ENHANCEMENT, the YAML zero-value validation (cortexproject#7700) and the
  ReadPartitionedGroupInfo error handling (cortexproject#7766) under BUGFIX.
- Folded the Go toolchain bump (cortexproject#7807, cortexproject#7814) into the existing build image
  entry, which now reads 1.27.0 rather than carrying a second entry for it.
- Folded cortexproject#7745 into cortexproject#7698: both are the same wipe-on-transient-DNS-failure bug,
  cortexproject#7698 on the A record path and cortexproject#7745 on the SRV path.
- Folded cortexproject#7743 into cortexproject#7640: both are panics in the active request tracker's
  truncation of match[]/query values.

Rebased again onto master, which added eight more entries. Same treatment:

- Sorted into their categories: the evaluation-delay-duration removal (cortexproject#7792)
  and the fifocache/ingester-metadata-streaming removals (cortexproject#7791) under CHANGE,
  the parquet max-block-label-names limit (cortexproject#7625), the non-pointer
  HistogramBucket slice (cortexproject#7809) and the merge iterator BatchSize (cortexproject#7823) under
  ENHANCEMENT, and the CSV-list empty-string fix (cortexproject#7714) under BUGFIX.
- Folded the Thanos/promql-engine refresh (cortexproject#7788) into the existing upgrade
  entry, which already carries cortexproject#7691, cortexproject#7505 and cortexproject#7740.

Signed-off-by: Charlie Le <charlie_le@apple.com>