RFR: 8346982: Remove JMX javadoc duplication that was in place due to JDK-6369229

[Kevin Walls]

Remove unnecessary javadoc duplication.

Both of these files:
src/java.management/share/classes/javax/management/modelmbean/DescriptorSupport.java
src/java.management/share/classes/javax/management/ImmutableDescriptor.java

..have two instances of this comment:
     // Note: this Javadoc is copied from javax.management.Descriptor
     //       due to 6369229.
	 	 
JDK-6369229 is long since resolved, the Javadoc duplication can be removed.

In the new doc build, we still have javadoc for equals() hashCode(), with e.g.:
"Description copied from interface: Descriptor"

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Commit messages:
 - 8346982: Remove JMX javadoc duplication that was in place due to JDK-6369229

Changes: https://git.openjdk.org/jdk/pull/25803/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25803&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8346982
  Stats: 93 lines in 2 files changed: 0 ins; 93 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/25803.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25803/head:pull/25803

PR: https://git.openjdk.org/jdk/pull/25803