[jdk11u-dev] RFR: 8240189: [TESTBUG] Some cgroup tests are failing after JDK-8231111

[Severin Gehwolf]

Please review this test fix backport to align with JDK 17+. Since [JDK-8231111](https://bugs.openjdk.java.net/browse/JDK-8231111) has been backported now, we need to adjust some test code so as to not run afoul when on certain test systems. The original patch doesn't apply cleanly due to:

 - `test/jdk/jdk/internal/platform/docker/MetricsMemoryTester.java`: [JDK-8275713](https://bugs.openjdk.java.net/browse/JDK-8275713) being present in JDK 11u which is a bug specific to JDK 15 and less.  JDK-8275713 is a partial backport of this bug. Omitted those hunks.
 - `test/lib/jdk/test/lib/containers/cgroup/MetricsTesterCgroupV1.java`: One hunk didn't apply cleanly due to [JDK-8250984](https://bugs.openjdk.java.net/browse/JDK-8250984) present in 11u ahead of this backport. Fixed this up manually.

Everything else is the same.

Testing:
- [x] container tests on Linux x86_64 on a cgroups v2 and cgroups v1 system. All pass.

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Commit messages:
 - Backport c92adf41587767e9c5c8e116cfaeb375d36928aa

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/956/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=956&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8240189
  Stats: 145 lines in 5 files changed: 46 ins; 28 del; 71 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/956.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/956/head:pull/956

PR: https://git.openjdk.java.net/jdk11u-dev/pull/956