[FIX] Downloads not working when `Content-Length` is not sent by the server

[JuancaG05]

Related Issues

App: https://github.com/owncloud/android/issues/4352 Also solves: https://github.com/owncloud/enterprise/issues/6697

• [x] Add changelog files for the fixed issues in folder changelog/unreleased. More info here
• [x] Add feature to Release Notes in ReleaseNotesViewModel.kt creating a new ReleaseNote() with String resources (if required)

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QA

[jesmrec]

Works for me. Ready to go in 4.2.2