Rename existing declarative policies on namesapce_agent_auth_mappings

MR: Rename "remote development cluster-agent" to "n... (!188305 - merged)

Description

As part of renaming the models highlighted in Rename remote development namespace agent auth ... (#516058 - closed) we would also need to be consistent and rename the associated declarative policies to match.

Acceptance Criteria

• rename the (admin|read)_remote_development_cluster_agent_mapping policies to (admin|read)_namespace_cluster_agent_mapping

Technical Requirements

Design Requirements

Impact Assessment

User Story