[`ruff`] Improve autofix safety for `never-union` (RUF020) #36283

Job	Run time
cargo fmt	20s
Determine changes	10s
pre-commit	38s
mkdocs	2m 44s
python package	1m 31s
cargo test (linux)	1m 48s
cargo clippy	2m 3s
cargo build (msrv)	4m 17s
cargo test (wasm)	1m 41s
cargo test (windows)	5m 35s
benchmarks	5m 14s
cargo build (release)	0s
cargo fuzz build	0s
cargo shear	23s
test scripts	1m 13s
formatter instabilities and black similarity	0s
test ruff-lsp	44s
ecosystem	2m 38s
fuzz parser	0s
	30m 59s

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