Fix default value of externalMyScaleDB.enabled (#321)

Disable external MyScaleDB by default

Author: BorisPolonsky

charts/dify/values.yaml

@@ -2619,7 +2619,7 @@ externalTencentVectorDB:
 # - these configs take effect only if both `externalWeaviate.enabled`, `externalQdrant.enabled` and `externalMilvus.enabled` and `externalPgvector.enabled` and `externalTencentVectorDB.enabled` are set as `false` and `externalMyScaleDB.enabled` is `true`
 ###################################
 externalMyScaleDB:
-  enabled: true
+  enabled: false
   host: "myscale"
   port: 8123
   username: "default"