[NPU][CI] change de trigger of release image workflow (#14969)

.github/workflows/release-docker-npu.yml

@@ -1,9 +1,10 @@
 name: Release Docker Images (NPU)
 on:
   push:
-    tags-ignore:
-      - "gateway-*" # Exclude gateway/router tags
-      - "router-*" # Exclude router tags
+    branches:
+      - main
+    paths:
+      - "python/sglang/version.py"
   pull_request:
     branches:
       - main
@@ -38,7 +39,6 @@ jobs:
             lmsysorg/sglang
           tags: |
             type=ref,event=pr
-            type=ref,event=tag,suffix=-cann${{ matrix.cann_version }}-${{ matrix.device_type }}
           flavor: |
             latest=false