Fix `ee/spec/frontend/analytics/cycle_analytics/components/create_value_stream_form/custom_stage_event_label_field_spec.js`

It seems like there is a problem with creating and overriding the store. When replacing

      store: {
        ...store,
        state: {
          defaultGroupLabels,
          ...state,
        },
        getters,
      },

with just store, it throws different errors. Our best guess is that the test file needs to be setup correctly by mocking the axios response for getGroupLabels