<i18n dev> RFR: 8378204: Remove AppContext from two Swing UI classes

[Phil Race]

A couple of missed cases of removing AppContext from Swing UI classes and one dead import

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Commit messages:
 - 8378204

Changes: https://git.openjdk.org/jdk/pull/29806/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29806&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8378204
  Stats: 14 lines in 3 files changed: 0 ins; 11 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/29806.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29806/head:pull/29806

PR: https://git.openjdk.org/jdk/pull/29806