refactor: use async methods instead of `Task.Run` in `AIAssistant` #4569

Job	Run time
Prepare version string	4s
Build / Build macOS (Intel)	5m 20s
Build / Build macOS (Apple Silicon)	2m 20s
Build / Build Linux (arm64)	3m 37s
Build / Build Windows ARM64	3m 55s
Build / Build Windows x64	3m 50s
Build / Build Linux	3m 29s
Package / Package Windows (win-arm64)	29s
Package / Package Linux (linux-x64)	56s
Package / Package Linux (linux-arm64)	59s
Package / Package macOS (osx-arm64)	23s
Package / Package Windows (win-x64)	30s
Package / Package macOS (osx-x64)	16s
	26m 8s

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