Overage modal: test cases

We need to consider multiple test cases when working with overage modal:

Free subscription: no overage modal is shown

Case	Related test
no overage modal is shown	manage_members_spec.rb#L105

Premium subscription:

Case	Related test
Show modal when adding a user by ID with role Guest to a group increases the users over subscription	manage_members_spec.rb#L114
Show modal when adding a user by ID with role Developer and higher to a group increases the users over subscription	manage_members_spec.rb#L115
Show modal when adding a user by email with role Guest to a group increases the users over subscription	manage_members_spec.rb#L117
Show modal when adding a user by email with role Developer and higher to a group increases the users over subscription	manage_members_spec.rb#L118
Show modal when adding a group with role Guest to a group increases the users over subscription	manage_groups_spec.rb#L95
Show modal when adding a group with role Developer and higher to a group increases the users over subscription	manage_groups_spec.rb#L96
Don't show modal if a receiving group is not enrolled into quarterly reconciliation	tested on Ultimate

Ultimate subscription:

Case	Related test
Don't show modal when adding a user with role Guest	manage_members_spec.rb#L176
Show modal when adding a user by ID with role Developer and higher to a group increases the users over subscription	manage_members_spec.rb#L177
Show modal when adding a user by email with role Developer and higher to a group increases the users over subscription	manage_members_spec.rb#L180
Don't show modal when adding a group with role Guest	manage_groups_spec.rb#L117
Show modal when adding a group with role Developer and higher to a group increases the users over subscription	manage_groups_spec.rb#L118
Don't show modal when adding a user with role Guest and group already has overage	Should be covered in #383238 (closed) manage_members_spec.rb#L189
Don't show modal if a receiving group is not enrolled into quarterly reconciliation	'when adding to a group not eligible for reconciliation' manage_members_spec.rb#L198