Tidy redux tests

[imnasnainaec]

• Change redux test files from .tsx to .ts
• Update mocking to avoid an eslint-disable- comment

This change is 

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.30%. Comparing base (9b4f75b) to head (12283aa).
⚠️ Report is 42 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3962      +/-   ##
==========================================
- Coverage   74.30%   74.30%   -0.01%     
==========================================
  Files         292      291       -1     
  Lines       10794    10792       -2     
  Branches     1352     1352              
==========================================
- Hits         8021     8019       -2     
  Misses       2387     2387              
  Partials      386      386              

Flag	Coverage Δ
backend	85.45% <ø> (ø)
frontend	65.69% <ø> (-0.02%)	⬇️

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[jasonleenaylor]

@jasonleenaylor reviewed 7 of 7 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @imnasnainaec)