title_bar: Simplify `git-ui` feature flag check #40682

Job	Run time
Check formatting and spelling	26s
Check Postgres and Protobuf migrations, mergability	14s
(Linux) Run Clippy and tests	9m 19s
(macOS) Run Clippy and tests	6m 52s
(Linux) Build Remote Server	1m 15s
(Windows) Run Clippy and tests	10m 7s
Linux arm64 release bundle	0s
Linux x86_x64 release bundle	0s
Create a macOS bundle	0s
Auto release preview	0s
	28m 13s

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