[XPU] Add registry mechanism for XPU CI tests (#25405)

Co-authored-by: Ma Mingfei <mingfei.ma@intel.com>

python/sglang/test/ci/ci_register.py

@@ -13,6 +13,7 @@ __all__ = [
     "register_cuda_ci",
     "register_amd_ci",
     "register_npu_ci",
+    "register_xpu_ci",
     "ut_parse_one_file",
 ]
 
@@ -107,9 +108,12 @@ def register_npu_ci(
 
 def register_xpu_ci(
     est_time: float,
-    suite: str,
+    suite: Optional[str] = None,
     nightly: bool = False,
     disabled: Optional[str] = None,
+    *,
+    stage: Optional[str] = None,
+    runner_config: Optional[str] = None,
 ):
     """Marker for XPU CI registration (parsed via AST; runtime no-op)."""
     return None