RFR: 8307193: Several Swing jtreg tests use class.forName on L&F classes

[Prasanta Sadhukhan]

Opensource couple RTL tests

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Commit messages:
 - 8307193: Several Swing jtreg tests use class.forName on L&F classes

Changes: https://git.openjdk.org/jdk/pull/19341/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19341&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8307193
  Stats: 328 lines in 2 files changed: 328 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/19341.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19341/head:pull/19341

PR: https://git.openjdk.org/jdk/pull/19341