Invalid prop warnings in pipelines from job_app.vue

Noticed a bunch of these errors in job log (example), made it a bit hard to read.

Contains a few dozen of these:

http://127.0.0.1:46563/assets/webpack/dll.9289f690039e/vendor.dll.bundle.js 376111:14 "[Vue warn]: Invalid prop: type check failed for prop "time". Expected String, got Boolean with value false. \n\nfound in\n\n---> \u003CCiHeader> at vue_shared/components/header_ci_component.vue\n \u003CJobPageApp> at jobs/components/job_app.vue\n \u003CRoot>"

Traced to this getter https://gitlab.com/gitlab-org/gitlab/-/blob/06ae32f386a5795e8859e4e490ed402f4da87196/app/assets/javascripts/jobs/store/getters.js#L4

if state.job.started is false this will return false and cause the warning.

Can maybe change to (state.job.started ? state.job.created_at : '') so it always at least returns a string.