🐛 Fix max-depth for collection-priority libraries

[aaronleopold]

Fixes a bug introduced from the fix which aimed to correct a regression in the scanner lol #423

The crux of the issue is outlined in the code to (hopefully) prevent a similar bug from slipping through the cracks again:

If the library is collection-priority, any child directories are 'ignored' and their files are part of / folded into the top-most folder (series).
If the library is not collection-priority, each subdirectory is its own series.
Therefore, we only scan one level deep when walking a series whose library is not collection-priority to avoid scanning duplicates which are part of other series

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 13 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
core/src/filesystem/scanner/series_scan_job.rs	0.00%	7 Missing ⚠️
core/src/filesystem/scanner/library_scan_job.rs	0.00%	6 Missing ⚠️

Files with missing lines	Coverage Δ
core/src/filesystem/scanner/library_scan_job.rs	0.00% <0.00%> (ø)
core/src/filesystem/scanner/series_scan_job.rs	0.00% <0.00%> (ø)