Fix failed job of form_spec.rb

What does this MR do and why?

What

Resolve #3276 (closed)

Fix failed job https://jihulab.com/gitlab-cn/gitlab/-/jobs/8524271

1.1) Failure/Error: super
          Selenium::WebDriver::Error::ElementClickInterceptedError:
            element click intercepted: Element <button id="dropdown-toggle-btn-6" data-testid="base-dropdown-toggle" aria-haspopup="listbox" aria-controls="base-dropdown-8" aria-labelledby="dropdown-toggle-btn-6" listeners="[object Object]" type="button" class="btn btn-default btn-md btn-block gl-button gl-text-gray-500! gl-new-dropdown-toggle">...</button> is not clickable at point (397, 391). Other element would receive the click: <div class="popover-body">...</div>
              (Session info: headless chrome=113.0.5672.126)

Why

The pop-up window blocked the button below, causing the test to report an error.

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