Add support for system messages not updating `channel.lastMessageAt` #11044

Job	Run time
Build Test App and Frameworks	6m 21s
Build LLC + UI (Xcode 14)	6m 11s
Automated Code Review	1m 17s
Test UI (Debug)	15m 51s
Build Demo App + Example Apps	14m 23s
Launch Allure TestOps	2m 44s
Test LLC (Debug)	18m 53s
Test Integration	14m 48s
Test E2E UI (Debug) (0)	32m 39s
Test E2E UI (Debug) (1)	38m 55s
	2h 32m 2s

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