MM-44351: Creates new Custom Group Admin system role. (#20573)

* MM-44351: Creates new Custom Group Admin system role.

* MM-44351: Adds missing test mock.

* MM-44351: Adds missing mocks.

testlib/store.go

@@ -68,6 +68,7 @@ func GetMockStoreForSetupFunctions() *mocks.Store {
 	systemStore.On("GetByName", model.MigrationKeyAddPlaybooksPermissions).Return(&model.System{Name: model.MigrationKeyAddPlaybooksPermissions, Value: "true"}, nil)
 	systemStore.On("GetByName", model.MigrationKeyAddCustomUserGroupsPermissions).Return(&model.System{Name: model.MigrationKeyAddCustomUserGroupsPermissions, Value: "true"}, nil)
 	systemStore.On("GetByName", model.MigrationKeyAddPlayboosksManageRolesPermissions).Return(&model.System{Name: model.MigrationKeyAddPlayboosksManageRolesPermissions, Value: "true"}, nil)
+	systemStore.On("GetByName", "CustomGroupAdminRoleCreationMigrationComplete").Return(&model.System{Name: model.MigrationKeyAddPlayboosksManageRolesPermissions, Value: "true"}, nil)
 	systemStore.On("InsertIfExists", mock.AnythingOfType("*model.System")).Return(&model.System{}, nil).Once()
 	systemStore.On("Save", mock.AnythingOfType("*model.System")).Return(nil)