[DS-1204] Set default value for creator_plugin options of the eventseries config

Steps to test:

[ ] log. in as a CMS user
[ ] install VY Log and Field UI modules
[ ] go to. /admin/structure/events/series/types/eventseries_type/live_stream/edit/form-display and enable Hosts name field
[ ] go to the event series
[ ] edit any event series > add instructor in Hosts name field and click on the Save button

Please check these boxes to confirm this PR covers the following cases:

Maintaining our upgrade path is essential. Check one or the other:
- [ ] This PR provides updates via hook_update_N or other means.
- [ ] No updates are necessary for this change.
Front end fixes should be tested against all of the Open Y Themes.
- [ ] Tested against Carnation
- [ ] Tested against Lily
- [ ] Tested against Rose
- [ ] This change does not contain front-end fixes.
[ ] I have flagged this PR "Needs Review" or pinged the VY devs/QA team in Slack