RFR: 8344066: Remove SecurityManager uses from the jdk.accessibility module

[Abhishek Kumar]

Since JEP 486 : Permanently Disable the Security Manager [JDK-8338625](https://bugs.openjdk.org/browse/JDK-8338625)
is now integrated, calls to java.security.AccessController.doPrivileged  and SecurityManager.checkPermission are obsolete and can be removed.

This PR takes care of the files in the jdk.accessibility module.

Tested swingset2 application with JAWS to verify a11y functionality on component. CI testing looks ok.

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Commit messages:
 - Remove obsolete AccessController.doPrivileged and SecurityManager.checkPermission calls in jdk.accessibility

Changes: https://git.openjdk.org/jdk/pull/22267/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22267&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8344066
  Stats: 64 lines in 3 files changed: 0 ins; 52 del; 12 mod
  Patch: https://git.openjdk.org/jdk/pull/22267.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22267/head:pull/22267

PR: https://git.openjdk.org/jdk/pull/22267