[jdk25u] RFR: 8364248: Separate commit and reservation limit detection

[Aleksey Shipilev]

This cleanup makes further backports in container code cleaner.

Additional testing:
 - [ ] Linux x86_64 server fastdebug, `hotspot_gc`

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Commit messages:
 - Backport ae11d8f44689502d35cb511e9ce288ab7cc0acae

Changes: https://git.openjdk.org/jdk25u/pull/355/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk25u&pr=355&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8364248
  Stats: 107 lines in 5 files changed: 45 ins; 38 del; 24 mod
  Patch: https://git.openjdk.org/jdk25u/pull/355.diff
  Fetch: git fetch https://git.openjdk.org/jdk25u.git pull/355/head:pull/355

PR: https://git.openjdk.org/jdk25u/pull/355