[Misc] Update model-specific PR tagging (#19949)

Signed-off-by: Roger Wang <hey@rogerw.me>

.github/mergify.yml

@@ -45,6 +45,7 @@ pull_request_rules:
       - files~=^vllm/entrypoints/openai/tool_parsers/llama.*\.py
       - files~=^vllm/model_executor/models/.*llama.*\.py
       - files~=^vllm/transformers_utils/configs/.*llama.*\.py
+      - title~=(?i)llama
   actions:
     label:
       add:
@@ -87,7 +88,6 @@ pull_request_rules:
       - files~=^vllm/model_executor/models/.*qwen.*\.py
       - files~=^vllm/reasoning/.*qwen.*\.py
       - title~=(?i)Qwen
-      - body~=(?i)Qwen
   actions:
     label:
       add: