Fix selector in editor component test

[kylebuss]

This addresses the querySelector made for querying the source quill editor placeholder text.

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This change is 

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.71%. Comparing base (bc7335d) to head (5c9d332).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3067   +/-   ##
=======================================
  Coverage   82.71%   82.71%           
=======================================
  Files         563      563           
  Lines       32667    32667           
  Branches     5306     5306           
=======================================
  Hits        27019    27019           
- Misses       4856     4868   +12     
+ Partials      792      780   -12     

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[Nateowami]

Reviewed 1 of 1 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @kylebuss)