[jfx21] RFR: 8311806: Class ButtonAccessibility is implemented twice

[Alexander Zuev]

Backport of the JDK-8311806 from main branch.

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Commit messages:
 - Backport ad5e66a7ca31994ecbdae3fc7d0b951e0a6f8197

Changes: https://git.openjdk.org/jfx/pull/1179/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1179&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8311806
  Stats: 7 lines in 3 files changed: 0 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jfx/pull/1179.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1179/head:pull/1179

PR: https://git.openjdk.org/jfx/pull/1179