fix for lag when opening sidebar using toggle sidebar brick

[grahamlangford]

What does this PR do?

• Fixes issue introduced in Sidepanel open check failing in some browsers #8271
• This was exposed by the toggle sidebar brick

Demo

https://www.loom.com/share/d6b96b187b2741d18eab4a9c35e99eb7

Checklist

• Designate a primary reviewer @twschiller

[codecov]

Codecov Report

Attention: Patch coverage is 42.85714% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 73.56%. Comparing base (bc5d406) to head (ef2f2a4).

Files	Patch %	Lines
src/contentScript/sidebarController.tsx	42.85%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8295      +/-   ##
==========================================
+ Coverage   73.55%   73.56%   +0.01%     
==========================================
  Files        1329     1329              
  Lines       40929    40931       +2     
  Branches     7565     7565              
==========================================
+ Hits        30105    30111       +6     
+ Misses      10824    10820       -4     

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[github-actions]

When the PR is merged, the first loom link found on this PR will be posted to #sprint-demo on Slack. Do not edit this comment manually.