[11u] RFR: 8227642: [TESTBUG] Make docker tests podman compatible

[Langer, Christoph]

Hi,

please help reviewing the backport of test fix 8227642: [TESTBUG] Make docker tests podman compatible.

Bug: https://bugs.openjdk.java.net/browse/JDK-8227642
Original Change: https://hg.openjdk.java.net/jdk/jdk/rev/709913d8ace9
Webrev: http://cr.openjdk.java.net/~clanger/webrevs/8227642.11u-dev.0/

Applying the patch rejected the hunk in  test/lib/jdk/test/lib/Platform.java. I, however, only had to place it correctly in the jdk11u-dev version of the file. The patch is prerequisite to backporting "8229284: [TESTBUG] jdk/internal/platform/cgroup/TestCgroupMetrics.java fails for - memory:getMemoryUsage" which we regularly see failing in our 11u regression testing.

Thanks
Christoph