fix: DS-1240 Fix recurring event description

[froboy]

Related Issue/Ticket:

PLEASE CHECK BASE BRANCH FOR YOUR PR
ONLY urgent and approved fixes for point release should go to master branch

https://yusa.atlassian.net/browse/DS-1240

Steps to test:

Empty description:

• Add a Live Stream or Virtual Event with no description
• Try to load the page

Series description:

• Add a description to the event series
• the description should show and the page should load

Instance description:

• Override the description on one instance
• the overridden description should show and the page should load

Quality checks:

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