ci: split emqx_bridge_kafka test in 3 groups

scripts/find-apps.sh

@@ -91,6 +91,10 @@ matrix() {
                 entries+=("$(format_app_entry "$app" 1 emqx "$runner")")
                 entries+=("$(format_app_entry "$app" 1 emqx-enterprise "$runner")")
                 ;;
+            apps/emqx_bridge_kafka)
+                entries+=("$(format_app_entry "$app" 1 emqx "$runner")")
+                entries+=("$(format_app_entry "$app" 3 emqx-enterprise "$runner")")
+                ;;
             apps/emqx_connector)
                 entries+=("$(format_app_entry "$app" 1 emqx "$runner")")
                 entries+=("$(format_app_entry "$app" 1 emqx-enterprise "$runner")")