fix: upsert single file

[alperozturk96]

• Tests written, or not not needed

Issue

Helps: #16139. Please read the issue first.

Changes

• Replaces CONFLICT_REPLACE with CONFLICT_IGNORE to prevent overwriting during insert.

• Tries insert first, then updates if the file already exists, instead of querying first.

  • This avoids race conditions: if two threads query at the same time, both might try the same action, but with insert-first, the database ensures atomicity, so the second thread sees the correct state.

• Auto-closes cursor using try-with-resources.

• Adds proper update logic if insert fails.

• Adds tests.

How to test?

• Upload a new file

[alperozturk96]

/backport to stable-3.35

[github-actions]

Codacy

SpotBugs

Category	Base	New
Bad practice	43	43
Correctness	74	74
Dodgy code	258	258
Experimental	1	1
Internationalization	7	7
Malicious code vulnerability	3	3
Multithreaded correctness	34	34
Performance	45	45
Security	18	18
Total	483	483

[github-actions]

APK file: https://www.kaminsky.me/nc-dev/android-artifacts/16146.apk



To test this change/fix you can simply download above APK file and install and test it in parallel to your existing Nextcloud app.

[github-actions]

blue-Light-Screenshot test failed, but no output was generated. Maybe a preliminary stage failed.