RFR: 8319673: Few security tests ignore VM flags [v2]

[Matthew Donovan]

> In this PR I updated the tests to use the newer ProcessTools.createTestJavaProcessBuilder() methods to launch child processes. This method ensures that VM options are passed to subprocesses.

Matthew Donovan has updated the pull request incrementally with one additional commit since the last revision:

  Including SignedJarWithCustomClassLoader.java which was missed in the first commit

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Changes:
  - all: https://git.openjdk.org/jdk/pull/17877/files
  - new: https://git.openjdk.org/jdk/pull/17877/files/96046d79..9620377e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17877&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17877&range=00-01

  Stats: 4 lines in 1 file changed: 1 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/17877.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17877/head:pull/17877

PR: https://git.openjdk.org/jdk/pull/17877