[Spec] Support logprobs with DSpark speculative decoding (#34696)

Co-authored-by: QAQEthan <QAQEthan@users.noreply.github.com>

test/registered/core/test_basic_sanity_dspark.py

@@ -8,7 +8,7 @@ from sglang.test.kits.basic_scheduler_stress_kit import BasicSchedulerStressMixi
 from sglang.test.kits.eval_accuracy_kit import GSM8KMixin
 from sglang.test.kits.fwd_occupancy_kit import FwdOccupancyMixin
 from sglang.test.kits.json_constrained_kit import JSONConstrainedMixin
-from sglang.test.kits.spec_server_kits import SpecGrammarKit
+from sglang.test.kits.spec_server_kits import SpecGrammarKit, SpecLogprobKit
 from sglang.test.test_utils import (
     DEFAULT_TIMEOUT_FOR_SERVER_LAUNCH,
     DEFAULT_URL_FOR_TEST,
@@ -38,6 +38,7 @@ class TestBasicSanityDSpark(
     GSM8KMixin,
     JSONConstrainedMixin,
     SpecGrammarKit,
+    SpecLogprobKit,
     CustomTestCase,
 ):
     served_model_name = TARGET_MODEL
@@ -88,10 +89,6 @@ class TestBasicSanityDSpark(
             },
         )
 
-    @unittest.skip("DSPARK rejects return_logprob at admission")
-    def test_grammar_logprob_count_matches_completion_tokens(self):
-        pass
-
     @classmethod
     def tearDownClass(cls):
         if cls.process is not None: