Align permission checks for `stop_environment`
Proposal
Simplify permissions in app/policies/environment_policy.rb to only allow stop_environment if user can update_environment. Execution of stop actions will occur with the original user so we don't need to check if the user is allowed to update these jobs.
We should also clarify this behavior in the documentation:
- clarify that user triggering the stop environment will only stop the environment.
- Side effects such as running stop actions will run with the original job's user.