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

test/registered/radix_cache/test_radix_attention.py

@@ -14,7 +14,7 @@ from sglang.test.test_utils import (
 )
 
 # RadixAttention server integration tests
-register_cuda_ci(est_time=100, stage="stage-b", runner_config="1-gpu-small")
+register_cuda_ci(est_time=100, stage="base-b", runner_config="1-gpu-small")
 register_amd_ci(est_time=100, suite="stage-b-test-1-gpu-small-amd")
 
 

test/registered/radix_cache/test_radix_cache_hit.py

@@ -11,7 +11,7 @@ from sglang.test.test_utils import (
     popen_launch_server,
 )
 
-register_cuda_ci(est_time=55, stage="stage-b", runner_config="1-gpu-small")
+register_cuda_ci(est_time=55, stage="base-b", runner_config="1-gpu-small")
 register_amd_ci(est_time=55, suite="stage-b-test-1-gpu-small-amd")
 
 MODEL = DEFAULT_SMALL_MODEL_NAME_FOR_TEST

test/registered/radix_cache/test_swa_radix_cache_kl.py

@@ -6,7 +6,7 @@ from sglang.test.server_fixtures.default_fixture import DefaultServerBase
 
 MODEL = "openai/gpt-oss-20b"
 
-register_cuda_ci(est_time=151, stage="stage-b", runner_config="1-gpu-large")
+register_cuda_ci(est_time=151, stage="base-b", runner_config="1-gpu-large")
 
 
 class TestSWARadixCacheKL(KLDivergenceMixin, DefaultServerBase):

test/registered/radix_cache/test_unified_radix_cache_kl.py

@@ -35,7 +35,7 @@ MAMBA_TRACK_INTERVAL = 128
 SWA_MODEL = "openai/gpt-oss-20b"
 FULL_MODEL = "Qwen/Qwen3-32B"
 
-register_cuda_ci(est_time=760, stage="stage-c", runner_config="4-gpu-h100")
+register_cuda_ci(est_time=760, stage="base-c", runner_config="4-gpu-h100")
 
 
 class UnifiedRadixTreeTestMixin: