Fix: pipeline failure by contributors_spec.js

What does this MR do and why?

Failed pipeline: https://jihulab.com/gitlab-cn/gitlab/-/pipelines/1096432/failures

Failed job: https://jihulab.com/gitlab-cn/gitlab/-/jobs/7207387

Failure:

FAIL jh/spec/frontend/contributors/components/contributors_spec.js
  ● Contributors charts › should render charts when loading completed and there is chart data
    expect(received).toMatchSnapshot()
    Snapshot name: `Contributors charts should render charts when loading completed and there is chart data 1`
    - Snapshot  - 0
    + Received  + 2
    @@ -21,10 +21,11 @@
            legendaveragetext="Avg"
            legendcurrenttext="Current"
            legendlayout="inline"
            legendmaxtext="Max"
            legendmintext="Min"
    +       legendseriesinfo=""
            option="[object Object]"
            responsive=""
            thresholds=""
            width="auto"
          />
    @@ -97,10 +98,11 @@
                legendaveragetext="Avg"
                legendcurrenttext="Current"
                legendlayout="inline"
                legendmaxtext="Max"
                legendmintext="Min"
    +           legendseriesinfo=""
                option="[object Object]"
                responsive=""
                thresholds=""
                width="auto"
              />
      56 |     expect(wrapper.find('.contributors-loader').exists()).toBe(false);
      57 |     expect(wrapper.find('.contributors-charts').exists()).toBe(true);
    > 58 |     expect(wrapper.element).toMatchSnapshot();
         |                             ^
      59 |   });
      60 | });
      61 |
      at Object.toMatchSnapshot (jh/spec/frontend/contributors/components/contributors_spec.js:58:29)
 › 1 snapshot failed.

Describe in detail what your merge request does and why.

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.