E2E test to test the new Project level security dashboard graph

As per gitlab-org/gitlab#235558 (closed) which failed gitlab-org/gitlab#280860 (closed) Initial iteration will click through to the Vulnerability Dashboard

This ticket covers off the next iteration of testing the new graph dashboard

Steps

1. Log into GitLab
2. Populate a project with vulnerability data
3. At project level select Security Dashboard
4. Ensure graph shows as expected (this may need some investigation into testing the graph widget, populating different results etc.)

Initial investigation

It turns out that the graph is populated from a cron job and is not real time. I need to investigate perhaps running this function. It might mean that the test is limited to running on master/nightly.