[jdk21u-dev] RFR: 8328262: Convert javax/swing/JSplitPane/8132123/bug8132123.java applet test to main

[Goetz Lindenmaier]

I backport this for parity with 21.0.9-oracle

-------------

Commit messages:
 - Backport c01095c0c9d4de1995d079be3356468196d9a25e

Changes: https://git.openjdk.org/jdk21u-dev/pull/2038/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=2038&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8328262
  Stats: 166 lines in 3 files changed: 77 ins; 89 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/2038.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/2038/head:pull/2038

PR: https://git.openjdk.org/jdk21u-dev/pull/2038