RFR: 8342707: Prepare Gatherers for graduation from Preview [v4]

[Viktor Klang]

> Make final adjustments to drop PreviewFeature and updating the @ since markers.

Viktor Klang has updated the pull request incrementally with one additional commit since the last revision:

  Updating the copyright year of the Gatherer benchmarks

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Changes:
  - all: https://git.openjdk.org/jdk/pull/21686/files
  - new: https://git.openjdk.org/jdk/pull/21686/files/6e8e1415..d4a6cfaa

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21686&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21686&range=02-03

  Stats: 11 lines in 11 files changed: 0 ins; 0 del; 11 mod
  Patch: https://git.openjdk.org/jdk/pull/21686.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21686/head:pull/21686

PR: https://git.openjdk.org/jdk/pull/21686