RFR: 8288287: Remove expired flags in JDK 21

[David Holmes]

It is that time of the release again. :)

The VM option flags that expire in JDK 21 are removed from the flags table.

The java manpage is updated in relation to the obsoleted and expired/removed  options.

Testing: tiers 1-3 sanity testing

Thanks.

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Commit messages:
 - 8288287: Remove expired flags in JDK 21

Changes: https://git.openjdk.org/jdk/pull/11603/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11603&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8288287
  Stats: 23 lines in 2 files changed: 11 ins; 10 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/11603.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11603/head:pull/11603

PR: https://git.openjdk.org/jdk/pull/11603