Add license granularity to Entity Maintainers execution

[chennn1990]

Description

Entity Maintainers availability depends on license tier (per feature matrix: Platinum and above by default), but some maintainers must be available on Basic, while others require Platinum+ (EA).

Based on the discussion, licensing must be evaluated at runtime (Kibana is not restarted on license changes), and maintainers should define their own minimum license requirement.

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Proposed Approach

Implement license-aware execution at the maintainer level:

• Each maintainer declares a minimum required license (configuration parameter)
• The Maintainers framework:
  • Checks the current license at execution time
  • Executes the maintainer only if the active license ≥ required license
• The license requirement parameter is optional
  • Defaults to Basic (explicitly set to Platinum where needed)

This provides flexibility to support maintainers targeting different license tiers in the future.

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Requirements

• Maintainers framework supports per-maintainer minLicense configuration
• License is evaluated at runtime, not only at startup
• Maintainers do not execute if license is insufficient
• Default license requirement is Basic
• Framework reacts correctly to license upgrades/downgrades without restart
• Clear logging when a maintainer is skipped due to license