[jdk11u-dev] RFR: 8291570: [TESTBUG] Part of JDK-8250984 absent from 11u

[Andrew John Hughes]

So, the story goes:

* [JDK-8250984](https://bugs.openjdk.org/browse/JDK-8250984) was backported in 11.0.10
* [JDK-8231111](https://bugs.openjdk.org/browse/JDK-8231111) was backported in 11.0.16
* In later JDKs, these changes occur in the opposite order. So, when 8250984 was backported, changes related to 8231111 were stripped from it.
* Now 8231111 has been backported, the testcase needs to be updated to recognise `OSCONTAINER_ERROR` (which is `-2`) as a valid return value from the CGroups v2 code.

Without this fix, we're seeing the testcase failing on newer systems. This change syncs the testcase with trunk.

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Commit messages:
 - 8291570: [TESTBUG] Part of JDK-8250984 absent from 11u

Changes: https://git.openjdk.org/jdk11u-dev/pull/1289/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=1289&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8291570
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/1289.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev pull/1289/head:pull/1289

PR: https://git.openjdk.org/jdk11u-dev/pull/1289