Delete Pipeline Schedule DOMContentLoaded handlers

Delete DOMContentLoaded handlers as they are unnecessary.

https://gitlab.com/groups/gitlab-org/-/epics/4541

app/assets/javascripts/pages/projects/pipeline_schedules/create/index.js

 import initForm from '../shared/init_form';
 
-document.addEventListener('DOMContentLoaded', initForm);
+initForm();

app/assets/javascripts/pages/projects/pipeline_schedules/edit/index.js

 import initForm from '../shared/init_form';
 
-document.addEventListener('DOMContentLoaded', initForm);
+initForm();

app/assets/javascripts/pages/projects/pipeline_schedules/new/index.js

 import initForm from '../shared/init_form';
 
-document.addEventListener('DOMContentLoaded', initForm);
+initForm();

app/assets/javascripts/pages/projects/pipeline_schedules/update/index.js

 import initForm from '../shared/init_form';
 
-document.addEventListener('DOMContentLoaded', initForm);
+initForm();