Refactor remote_development policy specs in accordance with matrix pattern

MR: Refactor agent_config_policy specs (!179304 - merged)

Description

Originates from the discussion here

We need to rewrite existing specs for remote_development policies that do not comply with the matrix spec pattern, to test all combinations and edge cases of the policy authorization logic. Policy should be tested against all roles and admin/non-admin combinations where applicable.

We also need to document this as a standard for policy specs in the remote development domain

Example of this pattern:

• ee/spec/policies/remote_development/workspace_policy_spec.rb

  # admin	# admin_mode	# licensed	workspace_owner	role_on_workspace_project	role_on_agent_project	allowed
  true	true	false	false	:none	:none	false
  false	false	false	true	:developer	:none	false
  false	false	true	true	:guest	:none	false
  false	false	false	false	:none	:maintainer	false
  false	false	true	false	:none	:developer	false
  true	false	true	false	:none	:none	false
  true	true	true	false	:none	:none	true
  false	false	true	true	:developer	:none	true
  false	false	true	false	:none	:maintainer	true

Acceptance Criteria

• Refactor ee/spec/policies/remote_development/remote_development_agent_config_policy_spec.rb
• Refactor ee/spec/policies/remote_development/workspaces_agent_config_policy_spec.rb
• Add new section to https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/lib/remote_development/README.md to document this standard
• Add the "policy debug helper" enable-able method to each spec (these are slightly different for each policy, and thus probably not worth trying to DRY up). Also document this pattern and the justifications behind "leaving debug code committed in specs".

Technical Requirements