Signal-android: After leaving a group I can still change disappearing messages setting

[pprucia]

I have:

• [x] searched open and closed issues for duplicates
• [x] read https://github.com/WhisperSystems/Signal-Android/wiki/Submitting-useful-bug-reports

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Bug description

I am in a group chat with someone and when I leave the group I am still able to change disappearing messages setting.

Steps to reproduce

• become a part of a group chat
• leave a group
• choose disappearing messages from menu
• change a setting

Actual result: Group members are sending messages with new setting.
Expected result: Disappearing messages settings can be changed only be existing members of a group chat.

Device info

Device: Multiple
Android version: 4.3+
Signal version: 3.25.4

[cascheberg]

I have implemented the UI fix in #5582.

[moxie0]

in 3.26.0