[jdk11u-dev] RFR: 8233712: Limit default tests jobs based on ulimit -u setting

[George Adams]

Applies cleanly. This backport is a prerequisite to landing https://github.com/openjdk/jdk11u-dev/pull/1277

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Depends on: https://git.openjdk.org/jdk11u-dev/pull/1307

Commit messages:
 - Backport 753c58b7f556fedd7828da487a34b8b228785ff9

Changes: https://git.openjdk.org/jdk11u-dev/pull/1308/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=1308&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8233712
  Stats: 43 lines in 4 files changed: 43 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/1308.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev pull/1308/head:pull/1308

PR: https://git.openjdk.org/jdk11u-dev/pull/1308