Revise developer access auth rule for agent project, on workspaces creation

MR: Pending

Description

Spin off from: !196578 (comment 2602276706)

We need to potentially reconsider the strong condition that the user needs to be a developer on the agent project after submitting a create workspace mutation. This is relevant given that we have other domain-level checks on workspace creation and separate auth policies that control mapping access that prevent the user from being able to see agents they are not permitted to use in the first place.

consult original design doc: https://gitlab.com/gitlab-org/workspaces/gitlab-workspaces-docs/-/blob/3af65b0683b6659376b58ec1a953925c1023dbe8/doc/tech-designs/2024-01-23-support-group-agent-authorization.md

Acceptance criteria

TODO

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• [If applicable, please list any technical requirements (performance, security, database, etc.)]

Implementation plan

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