### Description
Uploads with bulk_import defining --library fail with error 400 in the
REST API
The primary key of the track_type was changed from chars to a numerical
ID, and the data model expects this now in the REST endpoint. However
the bulk import still populates this field with the Char Tag.
### Testing Notes
**What I did:**
`libretime-api bulk_import --path /home/libretime/upload/ --library POD
--allowed-extensions mp3`
**How you can replicate my testing:**
see above
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Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
- change default storage path to /srv/libretime
- remove music dirs table
- use /tmp for testing storage
- storage dir should always have a trailing slash
