[jdk21u-dev] RFR: 8328238: Convert few closed manual applet tests to main

[Andrew Lu]

I backport this for parity with 21.0.5-oracle.

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Commit messages:
 - Backport 68170ae22233462e8925c75c4737be7f0ba9353d

Changes: https://git.openjdk.org/jdk21u-dev/pull/812/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=812&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8328238
  Stats: 395 lines in 4 files changed: 395 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/812.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/812/head:pull/812

PR: https://git.openjdk.org/jdk21u-dev/pull/812