RFR: 8227229: Deprecate the launcher -Xdebug/-debug flags that have not done anything since Java 6 [v6]

[Jaikiran Pai]

> Can I please get a review of this change which proposes to deprecate for removal the  `-Xdebug` option and `-debug` option of the `java` command? This addresses https://bugs.openjdk.org/browse/JDK-8227229.
> 
> As noted in the JBS issue this option is currently a no-op and has been there only for backward compatible since even Java 8 days.

Jaikiran Pai has updated the pull request incrementally with one additional commit since the last revision:

  remove -Xdebug usage from SourceDebugExtension test

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/14918/files
  - new: https://git.openjdk.org/jdk/pull/14918/files/b6c867b0..79c48cb0

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14918&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14918&range=04-05

  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/14918.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14918/head:pull/14918

PR: https://git.openjdk.org/jdk/pull/14918