RFR: 8355002: Clean up some mentions of "applet" in tests

[Phil Race]

This PR cleans up obsolete references to "applet" meaning
- the word applet in a comment where its not relevant (any more)
-  extraneous imports of the applet package or an applet class
-  obsolete methods which check for applet
- an exception handling case that isn't needed.

After this applet/Applet still appears in tests that test the Applet API but that's expected.

There's also a few tests that mention applets but aren't applet-specific and require more time than this quick clean up of most mentions.

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Commit messages:
 - 8355002
 - 8355002

Changes: https://git.openjdk.org/jdk/pull/24744/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24744&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8355002
  Stats: 346 lines in 42 files changed: 0 ins; 318 del; 28 mod
  Patch: https://git.openjdk.org/jdk/pull/24744.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24744/head:pull/24744

PR: https://git.openjdk.org/jdk/pull/24744