fix(useFeedbackForm): Cleanup after form is closed or submitted

[malwilley]

Without these changes, the form after being closed still prevented the page from scrolling. I'm not sure if this is intended or is a bug with the SDK, but I was able to fix this by removing from the DOM when the form was closed or submitted.

[codecov]

Codecov Report

Attention: Patch coverage is 88.88889% with 1 line in your changes missing coverage. Please review.

Project coverage is 78.20%. Comparing base (287eb32) to head (102ded2).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #74163      +/-   ##
==========================================
- Coverage   78.20%   78.20%   -0.01%     
==========================================
  Files        6660     6660              
  Lines      297379   297388       +9     
  Branches    51181    51182       +1     
==========================================
+ Hits       232554   232559       +5     
- Misses      58509    58513       +4     
  Partials     6316     6316              

Files	Coverage Δ
static/app/utils/useFeedbackForm.tsx	85.18% <88.88%> (+1.85%)	⬆️

... and 5 files with indirect coverage changes