[jdk21u-dev] RFR: 8302744: Refactor Hotspot container detection code

[Jan Kratochvil]

A patch 1 of 6 for: [[21u] Backport intention of 8322420: [Linux] cgroup v2: Limits in parent nested control groups are not detected](https://mail.openjdk.org/pipermail/jdk-updates-dev/2025-April/043206.html)

The backport is not clean:

- `src/hotspot/os/linux/cgroupV1Subsystem_linux.cpp` and `src/hotspot/os/linux/cgroupV2Subsystem_linux.cpp` are missing changed `CgroupV1Subsystem::memory_and_swap_usage_in_bytes()` as [JDK-8325139](https://github.com/openjdk/jdk/commit/3d106cb091de6b6ef2a9bf483fb0f5c98c28263c) has not been backported.

- `src/hotspot/os/linux/cgroupV1Subsystem_linux.cpp` and `src/hotspot/os/linux/cgroupV2Subsystem_linux.cpp` are missing changed `CgroupV1Subsystem::rss_usage_in_bytes()` as [JDK-8313083](https://github.com/openjdk/jdk/commit/c96cbe481c86800b76e220374b24b6671984adb7) has not been backported.

- deleted/renamed `test/hotspot/gtest/os/linux/test_cgroupSubsystem_linux.cpp` has missing `static` keywords as [JDK-8252136](https://github.com/openjdk/jdk/commit/09d4936657a0bdc122a4ab80735bd9c8c109839c) has not been backported.

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Commit messages:
 - 8302744: Refactor Hotspot container detection code

Changes: https://git.openjdk.org/jdk21u-dev/pull/1648/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1648&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8302744
  Stats: 1262 lines in 10 files changed: 688 ins; 436 del; 138 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1648.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1648/head:pull/1648

PR: https://git.openjdk.org/jdk21u-dev/pull/1648