[perf][spec decoding] Skip common_template in TRTLLMMLAMultiStepDraftBackend init (#26241)

python/sglang/srt/layers/attention/trtllm_mla_backend.py

@@ -1235,3 +1235,22 @@ class TRTLLMMLAMultiStepDraftBackend(FlashInferMLAMultiStepDraftBackend):
                 kv_indptr_buf=self.kv_indptr[i],
                 q_indptr_decode_buf=self.q_indptr_decode,
             )
+
+    def init_forward_metadata(self, forward_batch: ForwardBatch):
+        for i in range(self.speculative_num_steps - 1):
+            self.attn_backends[i].init_forward_metadata(forward_batch)
+
+    def init_forward_metadata_replay_cuda_graph(
+        self, forward_batch: ForwardBatch, bs: int
+    ):
+        for i in range(self.speculative_num_steps - 1):
+            self.attn_backends[i].init_forward_metadata_replay_cuda_graph(
+                bs,
+                forward_batch.req_pool_indices,
+                forward_batch.seq_lens,
+                seq_lens_sum=None,
+                encoder_lens=None,
+                forward_mode=ForwardMode.DECODE,
+                spec_info=forward_batch.spec_info,
+                seq_lens_cpu=forward_batch.seq_lens_cpu,
+            )