RFR: 8374232: Comment cleanup in diagnosticCommand.cpp

[Kevin Walls]

Comment-only cleanup, didn't spot during previous review.

Trivial, no code affected.

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Commit messages:
 - 8374232: Comment cleanup in diagnosticCommand.cpp

Changes: https://git.openjdk.org/jdk/pull/28962/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28962&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8374232
  Stats: 5 lines in 1 file changed: 0 ins; 1 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/28962.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28962/head:pull/28962

PR: https://git.openjdk.org/jdk/pull/28962