Update streaming.yml overlays to specify defaults

defaults/overlays/streaming.yml

@@ -50,6 +50,8 @@ external_templates:
 templates:
   mdb_streaming:
     default:
+      region: "US"
+      limit: "100000"
       originals_only: false
     optional:
       - use_<<key>>
@@ -170,4 +172,4 @@ overlays:
 
   hayu:
     variables: {key: "8", originals_key: hayu, weight: 10, allowed_libraries: show}
-    template: [name: standard, name: mdb_streaming]
+    template: [name: standard, name: mdb_streaming]