[jdk11u-dev] RFR: 8262379: Add regression test for JDK-8257746

[Jonathan Dowland]

Backport of [JDK-8262379](https://bugs.openjdk.java.net/browse/JDK-8262379) (Add regression test for JDK-8257746) for jdk11u-dev. Depends on #1020 . The added test passes for me (cgroups v2 system).

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Depends on: https://git.openjdk.java.net/jdk11u-dev/pull/1020

Commit messages:
 - 8262379: Add regression test for JDK-8257746

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/1066/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=1066&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8262379
  Stats: 56 lines in 1 file changed: 56 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/1066.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/1066/head:pull/1066

PR: https://git.openjdk.java.net/jdk11u-dev/pull/1066