RFR: 8366126: Feedback on two errors in JSR 400

[Weijun Wang]

Remove redundant `@spec` tags.

Note: the RMI spec fixed mentioned in the same bug will be fixed in the doc repo.

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Commit messages:
 - the fix

Changes: https://git.openjdk.org/jdk/pull/26945/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26945&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8366126
  Stats: 3 lines in 3 files changed: 0 ins; 3 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/26945.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26945/head:pull/26945

PR: https://git.openjdk.org/jdk/pull/26945