[red-knot] Migrate `is_disjoint_from` unit tests to Markdown tests #39097

Job	Run time
cargo build (release)	0s
mkdocs	2m 40s
Determine changes	9s
cargo fmt	21s
pre-commit	3m 19s
python package	1m 18s
cargo clippy	1m 55s
benchmarks	5m 41s
cargo build (msrv)	5m 49s
cargo fuzz build	4m 24s
cargo shear	29s
cargo test (linux)	1m 49s
cargo test (linux, release)	4m 0s
cargo test (wasm)	1m 36s
cargo test (windows)	6m 58s
test scripts	1m 0s
formatter instabilities and black similarity	0s
test ruff-lsp	44s
ecosystem	2m 39s
fuzz parser	0s
	44m 51s

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