[jdk21u-dev] RFR: 8316211: Open source several manual applet tests

[Andrew Lu]

I backport this for parity with 21.0.5-oracle.

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Commit messages:
 - Backport 2f311d59dcbbf7605e52fac0b8ebd35d7d51a48b

Changes: https://git.openjdk.org/jdk21u-dev/pull/777/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=777&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8316211
  Stats: 544 lines in 4 files changed: 544 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/777.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/777/head:pull/777

PR: https://git.openjdk.org/jdk21u-dev/pull/777