RFR: 8354447: Missing test for retroactive @SuppressWarnings("dangling-doc-comments") behavior

[Archie Cobbs]

This PR adds a regression test for the "retroactive" behavior of `@SuppressWarnings("dangling-doc-comments")`, that is,  the warning suppression applies to comments preceding the declaration that the annotation annotates, even though those comments are not within the lexical scope of that declaration. Previously there was no test for this behavior.

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Commit messages:
 - Add test for retroactive @SuppressWarnings("dangling-doc-comments") behavior.

Changes: https://git.openjdk.org/jdk/pull/24600/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24600&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8354447
  Stats: 10 lines in 1 file changed: 9 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/24600.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24600/head:pull/24600

PR: https://git.openjdk.org/jdk/pull/24600