[jdk8u-dev] RFR: 8284756: [11u] Remove unused isUseContainerSupport in CgroupV1Subsystem

[Jonathan Dowland]

Clean simple backport of 8284756 for jdk8u-dev cgroups v2 support.

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Depends on: https://git.openjdk.org/jdk8u-dev/pull/177

Commit messages:
 - 8284756: [11u] Remove unused isUseContainerSupport in CgroupV1Subsystem

Changes: https://git.openjdk.org/jdk8u-dev/pull/178/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=178&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8284756
  Stats: 2 lines in 1 file changed: 0 ins; 2 del; 0 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/178.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev pull/178/head:pull/178

PR: https://git.openjdk.org/jdk8u-dev/pull/178