fix: reject app-level vector-networks and vector-image, drop bridge from joined nets

The Docker daemon refuses any endpoint settings on the default bridge network and `docker compose` unconditionally attaches the service name as an alias on every joined network, so combining bridge with user-defined networks via compose's `networks:` block is impossible. When `vector-networks` is set, the compose template now joins only the configured networks; outbound to external sinks still works through user-defined network NAT. Additionally, `vector-image` and `vector-networks` are both global-only but `common.CommandPropertySet` silently accepts them at app level by merging global-only keys into the valid-property set, so both now reject explicitly in `validateSetValue`.

plugins/logs/templates/compose.yml.tmpl

@@ -15,7 +15,6 @@ services:
 
     {{- if $.VectorNetworks }}
     networks:
-      bridge: {}
       {{- range $name := $.VectorNetworks }}
       {{ $name }}: {}
       {{- end }}
@@ -32,9 +31,6 @@ services:
 {{- if $.VectorNetworks }}
 
 networks:
-  bridge:
-    name: bridge
-    external: true
   {{- range $name := $.VectorNetworks }}
   {{ $name }}:
     name: {{ $name }}