RFR: JDK-8308987: Update java.lang.Class to use javadoc snippets

[Joe Darcy]

Straightforward doc refactoring to use snippets.

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Commit messages:
 - JDK-8308987: Update java.lang.Class to use javadoc snippets

Changes: https://git.openjdk.org/jdk/pull/14194/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14194&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8308987
  Stats: 24 lines in 1 file changed: 0 ins; 0 del; 24 mod
  Patch: https://git.openjdk.org/jdk/pull/14194.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14194/head:pull/14194

PR: https://git.openjdk.org/jdk/pull/14194