RFR: 8357470: src/java.base/share/classes/sun/security/util/Debug.java implement the test for args.toLowerCase [v3]

[Mikhail Yankelevich]

> * added an automated mixed case option
> * using multithreading now
> * added logs for simpler debug
> * added missing -Djava.security.auth.debug coverage

Mikhail Yankelevich has updated the pull request incrementally with one additional commit since the last revision:

  comments & split test to 3

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Changes:
  - all: https://git.openjdk.org/jdk/pull/25391/files
  - new: https://git.openjdk.org/jdk/pull/25391/files/4f36b0f6..f23f2545

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25391&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25391&range=01-02

  Stats: 136 lines in 1 file changed: 91 ins; 5 del; 40 mod
  Patch: https://git.openjdk.org/jdk/pull/25391.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25391/head:pull/25391

PR: https://git.openjdk.org/jdk/pull/25391