fix(dbbackup): cannot use custom backup_storage

[lehoangnam040]

• after feat(backend): add storages to make usage of s3/sftp easier #10140 the STORAGES with dbbackup is override
• If I want to use custom backup_storage it will automatically fallback to use local storage
• the fixes here to allow uses dbbackup from InvenTree.backup

[netlify]

✅ Deploy Preview for inventree-web-pui-preview canceled.

Name	Link
🔨 Latest commit	0c28b2b
🔍 Latest deploy log	https://app.netlify.com/projects/inventree-web-pui-preview/deploys/690830568bedc1000850f8f3

[SchrodingersGat]

@lehoangnam040 thanks for the patch

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.85%. Comparing base (153bcc1) to head (0c28b2b).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #10751      +/-   ##
==========================================
- Coverage   87.85%   87.85%   -0.01%     
==========================================
  Files        1277     1277              
  Lines       57537    57539       +2     
  Branches     2018     2018              
==========================================
+ Hits        50549    50550       +1     
- Misses       6489     6490       +1     
  Partials      499      499              

Flag	Coverage Δ
backend	89.55% <100.00%> (-0.01%)	⬇️

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Components	Coverage Δ
Backend Apps	91.93% <ø> (ø)
Backend General	93.66% <ø> (ø)
Frontend	70.11% <ø> (ø)

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[github-actions]

💚 All backports created successfully

Status	Branch	Result
✅	1.1.x

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