Remove read_cluster_health permission

What does this MR do?

As a part of moving cluster health dashboard to the core #208224 (closed) it removes permission read_cluster_health from project, group and instance cluster policies. This rule was used to assure that given pricing tier has this feature included, and when #208224 (closed) will be completed this feature will be available to all tiers. From now on, only read_cluster rule will be restricting access to health tab in cluster show view.

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required) //Other parts of documentation will be update in separate MR when whole issue will be completed
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Separation of EE specific content