RFR: 8358729: jdk/internal/loader/URLClassPath/ClassnameCharTest.java depends on Applet [v4]

[Justin Lu]

> Please review this PR which finishes Applet removal for the test: jdk/internal/loader/URLClassPath/ClassnameCharTest.java.
> 
> `testclasses.jar` is updated such that the two classes no longer extend Applet.
> 
> 
> $ javap fo\ o.class 
> public class fo o {
> }
> $ javap æ$'\302\211'$'\302\213'å$'\302\206'$'\302\214'.class 
> public class 手册 {
> }
> 
> 
> The bug description of [JDK-8358729](https://bugs.openjdk.org/browse/JDK-8358729) contains the original `javap` output for those classes.
> 
> Additionally, the security APIs that were marked for removal are also removed from this test as well.

Justin Lu has updated the pull request incrementally with one additional commit since the last revision:

  Address offline review -> comments for maintainers, simplify exc and JAR_PATH

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/25703/files
  - new: https://git.openjdk.org/jdk/pull/25703/files/a9cad716..47f62aa2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25703&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25703&range=02-03

  Stats: 13 lines in 1 file changed: 5 ins; 1 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/25703.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25703/head:pull/25703

PR: https://git.openjdk.org/jdk/pull/25703