RFR: 8345286: Remove use of SecurityManager API from misc areas [v4]

[Jaikiran Pai]

> Can I please get a review of this change which removes usages of SecurityManager related APIs and some leftover related to SecurityManager changes?
> 
> This addresses https://bugs.openjdk.org/browse/JDK-8345286. Most of these changes are trivial. The `src/java.base/linux/classes/jdk/internal/platform/CgroupUtil.java` used to expose utility methods for dealing with SecurityManager permissions and it was called from a few places. That class is no longer needed with the clean up done in this PR.
> 
> No new tests have been introduced and tier testing is currently in progress.

Jaikiran Pai has updated the pull request incrementally with one additional commit since the last revision:

  Update src/java.base/linux/classes/jdk/internal/platform/cgroupv2/CgroupV2Subsystem.java
  
  Co-authored-by: Severin Gehwolf <jerboaa at gmail.com>

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/22478/files
  - new: https://git.openjdk.org/jdk/pull/22478/files/ad62bd4c..52a47f72

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22478&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22478&range=02-03

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/22478.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22478/head:pull/22478

PR: https://git.openjdk.org/jdk/pull/22478