Remove old is_sweep_pthread_p check in darray.h #9670

Job	Run time
make (yjit-bindgen, To fix: use patch in logs, --with-gcc=clang-14 --enable-yjit=dev --enable-zji...	5m 21s
make (check, RUSTC='rustc +1.58.0', 1.58.0)	5m 16s
cargo clippy	38s
make (check, --enable-yjit=dev, --yjit-call-threshold=1 --yjit-verify-ctx --yjit-code-gc, -T --yj...	6m 19s
make (test-bundled-gems, --enable-yjit=dev)	15m 48s
make (check, --enable-yjit=dev)	5m 28s
cargo test	56s
YJIT Ubuntu result	2s
	39m 48s

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