[Enhance] Increase DDP unit test timeout to 600s

Author: HAOCHENYE

ci/scripts/CI_ENV.sh

@@ -27,6 +27,9 @@ export PYTHONPYCACHEPREFIX=/tmp
 export TRITON_CACHE_DIR=/tmp/.triton
 export PYTEST_ADDOPTS='-o cache_dir=/tmp/.pytest_cache'
 
+# Some DDP test will cost more than 300s, set it to 600 avoid timeout error.
+export DISTRIBUTED_TESTS_DEFAULT_TIMEOUT=600
+
 proxy_off
 pip install -e .[all]