bots: Don't allow embedded bots bot type in production.

This is important for making it easy for us to merge code related to
UI for embedded bots now, without enabling them in the production UI.

zerver/models.py

@@ -494,12 +494,14 @@ class UserProfile(AbstractBaseUser, PermissionsMixin):
         DEFAULT_BOT,
         INCOMING_WEBHOOK_BOT,
         OUTGOING_WEBHOOK_BOT,
-        EMBEDDED_BOT,
     ]
+    if settings.DEVELOPMENT:
+        # Embedded bots are not yet enabled in production.
+        ALLOWED_BOT_TYPES.append(EMBEDDED_BOT)
 
     SERVICE_BOT_TYPES = [
         OUTGOING_WEBHOOK_BOT,
-        EMBEDDED_BOT
+        EMBEDDED_BOT,
     ]
 
     # Fields from models.AbstractUser minus last_name and first_name,