[BUG] `Probes.getLoadAndScaleToPercent` started to fail on some systems with JDK 24

[mishail]

Describe the bug

We started to see some strange test failures in our CI after #18085, where JDK 24 was introduced. AdmissionControlSingleNodeTests.testAdmissionControlRejectionMonitorOnlyMode and AdmissionControlSingleNodeTests.testAdmissionControlRejectionEnforcedMode specifically.

Those test expect requests to be rejected with a failure based on some CPU-load based policies, but that didn't happen for some reason. After spending some time I found that AverageCpuUsageTracker.getAverage started returning -1 in our CI.

Digging deeper I found that the cause is indeed in the security.policy (similar to #18548).
So with JDK 24 these permissions are now required as well:

  permission java.io.FilePermission "/sys/fs/cgroup/cpu.max", "read";
  permission java.io.FilePermission "/sys/fs/cgroup/cpu.weight", "read";
  permission java.io.FilePermission "/sys/fs/cgroup/cpuset.cpus", "read";
  permission java.io.FilePermission "/sys/fs/cgroup/cpuset.cpus.effective", "read";

I'can tell which exactly systems might be affected as I wasn't able to reproduce on my macOS and build.ci.opensearch.org doesn't have these failures.

These are the stack traces to prove my point:

• https://gist.github.com/Mishail/3cfe66d357d7be45278af948837bcb36
• https://gist.github.com/Mishail/dc22658c295daad9935d0558e55f465a
• https://gist.github.com/Mishail/81aee4e8805e1c434a576d37c957c28b
• https://gist.github.com/Mishail/b3ae3365729f378f5df5df629abdaad4
• https://gist.github.com/Mishail/dcaec18dd447c12c4241a033da345b70

Related component

Build

To Reproduce

Run ./gradlew test on a system that uses CgroupV2Subsystem implementation of CgroupSubsystem

Expected behavior

Tests pass

Additional Details

No response

[mishail]

cc @reta

[reta]

cc @reta

Thanks @mishail , would you like to PR those as well? thank you