RBAC: No need to filter permissions on cache hit

[gamab]

What is this feature?

Small optimisation on the search user permission: on cache hit we do not need to filter permissions.

Why do we need this feature?

[Add a description of the problem the feature is trying to solve.]

Who is this feature for?

[Add information on what kind of user the feature is for.]

Which issue(s) does this PR fix?:

Fixes #

Special notes for your reviewer:

Please check that:

• It works as expected from a user's perspective.
• If this is a pre-GA feature, it is behind a feature toggle.
• The docs are updated, and if this is a notable improvement, it's added to our What's New doc.