Relax "test" runnable check (#15647)

This commit updates the Tree-sitter query to match Rust attributes
containing the word "test". The previous query only matched attributes
with the exact string "test", which was too restrictive for custom test
macros like https://docs.rs/test-log/0.2.10/test_log/#

Discussion - https://github.com/zed-industries/zed/discussions/15580