Only return and handle 409 responses during save requests

[max-nextcloud]

Describe the bug We currently also return and handle 409 responses during sync requests. This leads to two possible scenarios that can create such responses. In addition the 409 will always include both - the sync data and the updated content of the file. This is send again and again.

To Reproduce Steps to reproduce the behavior:

1. Open a file, create some versions, save the file
2. keep editing and revert to a previous version
3. See a conflict dialogue right away and inspect the network tab
4. See ongoing 409 responses to sync requests.

Expected behavior Only see 409 responses to save requests.

Screenshots and logs Will be added later.