Project policy EE secrets permissions refactor

What does this MR do and why?

This MR refactors the project secrets permissions. Previously, different user roles (reporter, maintainer, owner) had their permissions for managing secrets scattered throughout the code in separate rules. The update consolidates this by moving all secrets-related permissions to the appropriate role sections and adds a single rule that disables all secrets functionality when the secrets manager feature is turned off. This makes the code cleaner and easier to maintain while ensuring that secrets permissions are properly controlled based on user roles and feature availability.

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