[jdk21u-dev] RFR: 8327835: Convert java/awt/FileDialog/RegexpFilterTest/RegexpFilterTest applet test to main

[Goetz Lindenmaier]

I backport this for parity with 21.0.9-oracle

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Commit messages:
 - Backport d25c452f0c4a2106a1fa06b56039f0f0b5d6e952

Changes: https://git.openjdk.org/jdk21u-dev/pull/2032/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=2032&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8327835
  Stats: 344 lines in 4 files changed: 74 ins; 270 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/2032.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/2032/head:pull/2032

PR: https://git.openjdk.org/jdk21u-dev/pull/2032