RFR: 8343486: Remove unnecessary @SuppressWarnings annotations and -Xlint:-foo options

[Archie Cobbs]

Please review this patch which removes unnecessary `@SuppressWarnings` annotations and `-Xlint:-foo` options.

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Commit messages:
 - Remove unnecessary @SuppressWarnings annotations and -Xlint:-key flags.

Changes: https://git.openjdk.org/jdk/pull/21859/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21859&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8343486
  Stats: 115 lines in 13 files changed: 0 ins; 111 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/21859.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21859/head:pull/21859

PR: https://git.openjdk.org/jdk/pull/21859