RFR: 8344969: Remove the jmx.mxbean.multiname compatibility property [v2]

[Kevin Walls]

> Remove the System Property "jmx.mxbean.multiname" which was introduced in JDK-7 for compatibility with code which may have depended on previous incorrect behaviour.  Removal is long overdue.

Kevin Walls has updated the pull request incrementally with one additional commit since the last revision:

  test update/simplification

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Changes:
  - all: https://git.openjdk.org/jdk/pull/23131/files
  - new: https://git.openjdk.org/jdk/pull/23131/files/7b85bfbf..3fb85cd4

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23131&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23131&range=00-01

  Stats: 13 lines in 1 file changed: 0 ins; 10 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/23131.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23131/head:pull/23131

PR: https://git.openjdk.org/jdk/pull/23131