cli: Tweak default thread count logic #1098

Job	Run time
Ensure 'cargo fmt' has been run	13s
Extract crate metadata	4s
Minimum supported rust version	1m 19s
aarch64-unknown-linux-gnu (ubuntu-20.04)	4m 36s
arm-unknown-linux-gnueabihf (ubuntu-20.04)	5m 11s
arm-unknown-linux-musleabihf (ubuntu-20.04)	4m 23s
i686-pc-windows-msvc (windows-2019)	4m 2s
i686-unknown-linux-gnu (ubuntu-20.04)	4m 7s
i686-unknown-linux-musl (ubuntu-20.04)	3m 25s
x86_64-apple-darwin (macos-12)	2m 56s
x86_64-pc-windows-gnu (windows-2019)	4m 30s
x86_64-pc-windows-msvc (windows-2019)	4m 29s
x86_64-unknown-linux-gnu (ubuntu-20.04)	4m 19s
x86_64-unknown-linux-musl (ubuntu-20.04)	4m 24s
Publish to Winget	0s
	47m 58s

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