Fix file cache initialization

[bugmakerrrrrr]

Description

When a search node starts, a file cache is initialized. The size of the file cache is determined by available space of the local storage and the user's config (Math.min(capacity, availableCapacity)). However, this approach can cause a issues. For example, if we have a search node with 100GB local storage and config the file cache to be 80GB, after some time, 90% of the file cache is used. if we then restart the node, the available space may be reduced to just 28GB, which means the file cache will also be reduced to 28GB. This can cause further issues as the fs stats will be adjusted based on the file cache size, leading to wired results.

To address this issue, we can use the total space to calculate the size of file cache. User can config the size to be absolute bytes value or a percentage of total space.

Related Issues

Resolves #[Issue number to be closed when this PR is merged]

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• API changes companion pull request created.
• Failing checks are inspected and point to the corresponding known issue(s) (See: Troubleshooting Failing Builds)
• Commits are signed per the DCO using --signoff
• Commit changes are listed out in CHANGELOG.md file (See: Changelog)
• Public documentation issue/PR created

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[bugmakerrrrrr]

@andrross @kotwanikunal could you please take a look when you get a chance

[github-actions]

❌ Gradle check result for 328da32: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[github-actions]

✅ Gradle check result for afe886f: SUCCESS

[codecov]

Codecov Report

Attention: Patch coverage is 76.31579% with 9 lines in your changes missing coverage. Please review.

Project coverage is 71.75%. Comparing base (b15cb0c) to head (bd73b60).
Report is 484 commits behind head on main.

Files	Patch %	Lines
server/src/main/java/org/opensearch/node/Node.java	76.66%	4 Missing and 3 partials ⚠️
...c/main/java/org/opensearch/monitor/fs/FsProbe.java	60.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #14004      +/-   ##
============================================
+ Coverage     71.42%   71.75%   +0.33%     
- Complexity    59978    62165    +2187     
============================================
  Files          4985     5125     +140     
  Lines        282275   292385   +10110     
  Branches      40946    42249    +1303     
============================================
+ Hits         201603   209795    +8192     
- Misses        63999    65306    +1307     
- Partials      16673    17284     +611     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[bugmakerrrrrr]

@andrross friendly ping :)

[github-actions]

❕ Gradle check result for bd73b60: UNSTABLE

Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.