[jdk21u-dev] RFR: 8328247: Remove redundant dir for tests converted from applet to main

[Satyen Subramaniam]

Backporting JDK-8328247: Remove redundant dir for tests converted from applet to main. Renames three javax swing tests, as per change accepted by Oracle.

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Commit messages:
 - Backport ece4124f25f676da9bf2d1b7fd8e4394dd7d31af

Changes: https://git.openjdk.org/jdk21u-dev/pull/2276/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=2276&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8328247
  Stats: 0 lines in 3 files changed: 0 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/2276.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/2276/head:pull/2276

PR: https://git.openjdk.org/jdk21u-dev/pull/2276