ci: remove IS_BLACKWELL env var; auto-detect Blackwell (#21118)

python/sglang/srt/environ.py

@@ -194,7 +194,6 @@ class Envs:
     SGLANG_TEST_STUCK_SCHEDULER_INIT = EnvFloat(0)
     SGLANG_TEST_STUCK_TOKENIZER = EnvFloat(0)
     SGLANG_TEST_CRASH_AFTER_STREAM_OUTPUTS = EnvInt(0)
-    IS_BLACKWELL = EnvBool(False)
     IS_H200 = EnvBool(False)
     SGLANG_SET_CPU_AFFINITY = EnvBool(False)
     SGLANG_PROFILE_WITH_STACK = EnvBool(True)

python/sglang/test/test_utils.py

@@ -37,6 +37,7 @@ from sglang.srt.environ import envs
 from sglang.srt.utils import (
     get_bool_env_var,
     get_device,
+    is_blackwell,
     is_cuda,
     is_xpu,
     kill_process_tree,
@@ -197,8 +198,8 @@ def is_in_amd_ci():
 
 
 def is_blackwell_system():
-    """Return whether it is running on a Blackwell (B200) system."""
-    return envs.IS_BLACKWELL.get()
+    """Same CUDA capability + toolkit semantics as ``sglang.srt.utils.is_blackwell``."""
+    return is_blackwell()
 
 
 def is_h200_system():