RFR: 8253714: [cgroups v2] Soft memory limit incorrectly using memory.high [v2]

[Severin Gehwolf]

> Tests using `--memory-reservation` started to fail with newer `crun` cgroups v2-capable runtime. It turns out it was
> incorrectly setting `memory.high` in an early version and got fixed to set `memory.low` now instead. This change
> accounts for that.

Severin Gehwolf has refreshed the contents of this pull request, and previous commits have been removed. The
incremental views will show differences compared to the previous content of the PR. The pull request contains one new
commit since the last revision:

  8253714: [cgroups v2] Soft memory limit incorrectly using memory.high

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/381/files
  - new: https://git.openjdk.java.net/jdk/pull/381/files/c3337bc6..25d131d8

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=381&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=381&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/381.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/381/head:pull/381

PR: https://git.openjdk.java.net/jdk/pull/381