cli: make the build faster (#245705)

codegen-units=1 lets the compiler optimize more aggressively, but it
makes things _much_ slower. The benefits of this has been evaporating
as the compiler has improved, and now that the CLI build is a bottleneck,
let's just remove it.

cli/Cargo.toml

@@ -77,7 +77,6 @@ russh-keys = { git = "https://github.com/microsoft/vscode-russh", branch = "main
 [profile.release]
 strip = true
 lto = true
-codegen-units = 1
 
 [features]
 default = []