Cleanup remote_development_namespace_agent_authorization feature flag

Issue: [Feature flag] Cleanup `remote_development_name... (#474784 - closed)

What does this MR do and why?

This MR cleans up the remote_development_namespace_agent_authorization feature flag and modifies tests to reflect the cleanup.

Cleanup remote_development_namespace_agent_authorization feature flag Changelog: other

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots

How to set up and validate locally

pre-req: Setup GDK with remote development locally

• create a group say g1 and a subgroup g2
• create a project under g2 with a devfile setup for workspace creation
• in group g1 have an agent configuration setup and connect it with gitlab see point 10 and point 11 here
• Attempt to create a workspace with the project created under g2. Result: no agents are available to create a workspace
• Under group g1, go to workpsaces settings. Result: Your agent is not in the allowed agent section, and it should be under all agents and blocked
• Click allow for your agent
• Attempt to create a workspace with the project created under g2 again, Result: the created agent is available to create a workspace
• Create workspace and access it and validate it is working as expected

Numbered steps to set up and validate the change are strongly suggested.