[3.1 backport] Introduced setting for disabling denormalized privilege data structures

[nibix]

Description

Backport from #5465

This introduces the setting plugins.security.privileges_evaluation.precomputed_privileges.enabled which can be used to disable the creation of denormalized privilege data structures. It is enabled by default to provide the best action throughput. It can make sense to disable the setting when it is seen that the initialisation process takes so much time/resources that it negatively affects the cluster performance (like observed in #5464) . This come at the price of a reduced action throughput.

• Category: Enhancement
• Why these changes are required? Operational safety
• What is the old behavior before changes and new behavior after changes? No behavioral changes.

Testing

• Unit testing

Check List

• New functionality includes testing
• New functionality has been documented
• Commits are signed per the DCO using --signoff

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[nibix]

The checks are in a weird state ... according to https://github.com/opensearch-project/security/pull/5483/checks all checks are green. Not sure how to proceed. 🤔

[nibix]

@cwperks @shikharj05 I could not find any way to fix the stuck checks, so I filed a replacement PR at #5484

[nagarajg17]

@nibix Looks like replacement PR is in similar state #5484

[cwperks]

@nibix They are not stuck. We need to update the branch protection rules to remove these required checks in 3.1. We do not run checks against JVM < 21 for 3.x line.

[nibix]

Thank you for merging!