[red-knot] Fix file watching for new non-project files #41213

Job	Run time
cargo build (release)	0s
Determine changes	12s
cargo fmt	19s
mkdocs	2m 32s
pre-commit	3m 23s
python package	1m 21s
benchmarks	6m 13s
cargo build (msrv)	2m 3s
cargo fuzz build	4m 6s
cargo clippy	1m 53s
cargo shear	24s
cargo test (linux, release)	4m 4s
cargo test (wasm)	1m 34s
cargo test (linux)	2m 5s
cargo test (windows)	5m 38s
formatter instabilities and black similarity	0s
test scripts	1m 8s
test ruff-lsp	39s
ecosystem	20s
fuzz parser	0s
	37m 54s

Provide feedback