revert logic from event conversations PRs

[mahibi]

.. while making sure logic from near/far future events remains and archived conversation handling is fixed (must not show up in main conversations list).

🖼️ Screenshots

🏚️ Before	🏡 After
B	A

🚧 TODO

• ...

🏁 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]

@sowjanyakch please check if i oversaw something that was solved with your PRs but not with this one

[github-actions]

Codacy

Lint

Type	master	PR
Warnings	99	99
Errors	10	10

SpotBugs

Category	Base	New
Bad practice	6	6
Correctness	222	16
Dodgy code	71	67
Internationalization	3	3
Malicious code vulnerability	3	3
Performance	4	4
Security	1	1
Total	310	100

[github-actions]

APK file: https://www.kaminsky.me/nc-dev/android-artifacts/5003-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.

[sowjanyakch]

Event conversations that take place after 16 hours are excluded from filter. If you create an event conversation that occurs after 16 hours, post a message, and mark it as unread, it won’t show up under the “Unread” filter. This is the same case for unread mentions and archived filters.

[mahibi]

will take a closer later.
So not merging for v21.1