fix duplicate messages because of multiple scopes

[mahibi]

fix #4764
this replaces #4801

(also see #4688 for a similar fix where the scope handling was introduced)

🏁 Checklist

• ⛑️ Tests (unit and/or integration) are included or not needed
• 🔖 Capability is checked or not needed
• 🔙 Backport requests are created or not needed: /backport to stable-xx.x
• 📅 Milestone is set
• 🌸 PR title is meaningful (if it should be in the changelog: is it meaningful to users?)

[mahibi]

if it turns out that canceling the scope in onPause is problematic, then we should have a closer look on this chain and analyze why GetCapabilitiesInitialLoadState is called again (e.g. after coming back from taking a photo) which leads to the multiple scopes:

GetCapabilitiesInitialLoadState > chatViewModel.loadMessages > chatRepository.initScopeAndLoadInitialMessages > creates multiple scopes

[github-actions]

Codacy

Lint

Type	master	PR
Warnings	98	97
Errors	9	9

SpotBugs

Category	Base	New
Bad practice	6	6
Correctness	222	220
Dodgy code	71	71
Internationalization	3	3
Malicious code vulnerability	3	3
Performance	4	4
Security	1	1
Total	310	308

[github-actions]

APK file: https://www.kaminsky.me/nc-dev/android-artifacts/4812-talk.apk



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