[CI] Rename basic CI stage-a/b/c -> base-a/b/c for symmetry with extra CI (#25420)

test/registered/profiling/test_profile_v2.py

@@ -19,7 +19,7 @@ from sglang.test.test_utils import (
 
 register_cuda_ci(
     est_time=120,
-    stage="stage-b",
+    stage="base-b",
     runner_config="1-gpu-small",
     disabled="Temporarily disabled",
 )

test/registered/profiling/test_start_profile.py

@@ -29,7 +29,7 @@ from sglang.test.test_utils import (
     popen_launch_server,
 )
 
-register_cuda_ci(est_time=42, stage="stage-b", runner_config="1-gpu-small")
+register_cuda_ci(est_time=42, stage="base-b", runner_config="1-gpu-small")
 register_amd_ci(est_time=60, suite="stage-b-test-1-gpu-small-amd")
 
 OUTPUT_DIR = "./profiler_dir"