Add `UV_NO_BUILD_ISOLATION` as environment variable #5614

Job	Run time
cargo test \| windows	4m 30s
cargo test \| ubuntu	3m 57s
build binary \| linux	1m 38s
cargo test \| macos	4m 3s
build binary \| macos aarch64	1m 47s
build binary \| macos x86_64	1m 45s
build binary \| windows	3m 56s
cargo clippy \| ubuntu	45s
cargo fmt	21s
check windows trampoline	4m 19s
cargo clippy \| windows	4m 23s
ecosystem test \| prefecthq/prefect	2m 0s
ecosystem test \| pallets/flask	10s
check system \| python on debian	42s
check cache \| ubuntu	1m 2s
check system \| python on fedora	39s
check system \| amazonlinux	25s
check system \| alpine	27s
check system \| python on opensuse	33s
check system \| python via pyenv	1m 44s
check system \| pypy on ubuntu	28s
check system \| pyston	3m 51s
check system \| python on rocky linux 8	31s
check system \| python on ubuntu	17s
check system \| python on rocky linux 9	31s
check cache \| macos aarch64	12s
check system \| python on macos x86_64	42s
check system \| python on macos aarch64	14s
check system \| homebrew python on macos aarch64	18s
check system \| python3.10 on windows	36s
check system \| python3.10 on windows x86	55s
check system \| python3.12 via chocolatey	1m 19s
check system \| conda3.8 on linux	1m 25s
check system \| conda3.11 on linux	41s
check system \| embedded python3.10 on windows	29s
check system \| python3.13 on windows	1m 32s
check system \| conda3.8 on windows	2m 10s
check system \| conda3.11 on windows	2m 2s
check system \| conda3.8 on macos	46s
check system \| conda3.11 on macos	44s
	58m 49s

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