fix: total file count update on add and delete

[KristinAoki]

JIRA Ticket: TNL-10958

I had 29 files, uploaded 5, and then had 32 files. But it showed this:

Testing

1. Navigate to the Videos Page
2. Add multiple videos
3. Check that row status count equals the expected amount
4. Delete at least two videos
5. Check that row status count equals the expected amount

*repeat for the Files page

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (e41efba) 87.97% compared to head (ddfa02a) 87.95%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #681      +/-   ##
==========================================
- Coverage   87.97%   87.95%   -0.02%     
==========================================
  Files         415      415              
  Lines        6396     6387       -9     
  Branches     1379     1379              
==========================================
- Hits         5627     5618       -9     
  Misses        745      745              
  Partials       24       24              

Files	Coverage Δ
src/files-and-videos/files-page/FilesPage.jsx	100.00% <100.00%> (ø)
src/files-and-videos/files-page/data/slice.js	94.73% <ø> (-0.27%)	⬇️
src/files-and-videos/files-page/data/thunks.js	100.00% <100.00%> (ø)
src/files-and-videos/generic/FileTable.jsx	97.10% <100.00%> (+0.04%)	⬆️
src/files-and-videos/videos-page/VideosPage.jsx	100.00% <100.00%> (ø)
src/files-and-videos/videos-page/data/slice.js	95.83% <ø> (-0.17%)	⬇️
src/files-and-videos/videos-page/data/thunks.js	98.11% <100.00%> (-0.04%)	⬇️
...-videos/videos-page/factories/mockApiResponses.jsx	100.00% <ø> (ø)

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