RFR: 8326957: Implement JEP 474: ZGC: Generational Mode by Default [v6]

[Axel Boldt-Christmas]

> This is the implementation task for `JEP 474: ZGC: Generational Mode by Default`. See the JEP for details. [JDK-8326667](https://bugs.openjdk.org/browse/JDK-8326667)

Axel Boldt-Christmas has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 11 commits:

 - Merge remote-tracking branch 'upstream_jdk/master' into JDK-8326957
 - Revert "Default to non generational ZGC with JVMCI"
   
   This reverts commit 4de30da2661c64ae00d13a5e15a1a61fcb667a10.
 - Default to non generational ZGC with JVMCI
 - Merge tag 'jdk-23+21' into JDK-8326957
   
   Added tag jdk-23+21 for changeset e833bfc8
 - Merge tag 'jdk-23+19' into JDK-8326957
   
   Added tag jdk-23+19 for changeset 706b421c
 - Remove extra space
 - Use consistent terminology
 - Merge tag 'jdk-23+17' into JDK-8326957
   
   Added tag jdk-23+17 for changeset 8efd7aa6
 - Merge tag 'jdk-23+16' into JDK-8326957
   
   Added tag jdk-23+16 for changeset d580bcf9
 - Update VMDeprecatedOptions.java test
 - ... and 1 more: https://git.openjdk.org/jdk/compare/5ded8da6...60460dce

-------------

Changes: https://git.openjdk.org/jdk/pull/18393/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18393&range=05
  Stats: 107 lines in 7 files changed: 105 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/18393.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18393/head:pull/18393

PR: https://git.openjdk.org/jdk/pull/18393