[jdk11u-dev] RFR: 8312049: runtime/logging/ClassLoadUnloadTest can be improved

[Daniel Hu]

Backport that improves ClassLoadUnloadTest; already backported to [JDK21](https://github.com/openjdk/jdk21u-dev/pull/909) and [JDK17](https://github.com/openjdk/jdk17u-dev/pull/2806). Original commit does not apply cleanly due to the options "-Xlog:class+load+cause" "-Xlog:class+load+cause+native" were not added until a later [version](https://bugs.openjdk.org/browse/JDK-8193513), thus these cases are excluded. Some args in exec() also were not added until a [later version](https://bugs.openjdk.org/browse/JDK-8289184), thus they are excluded. Additionally, [these flags](https://bugs.openjdk.org/browse/JDK-8256718) were deprecated in a later version and thus removed from this test; simple modifications are added so that these later removed cases follow the backport logic. Affected test passes.

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Commit messages:
 - Backport 4676b40f17dd18941f5883cb9b989ad639992a50

Changes: https://git.openjdk.org/jdk11u-dev/pull/2920/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2920&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8312049
  Stats: 42 lines in 1 file changed: 3 ins; 6 del; 33 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2920.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2920/head:pull/2920

PR: https://git.openjdk.org/jdk11u-dev/pull/2920