Set missing secrets for fleet_configurable fields in cloudera, mongo, silverstripe_cms (DataDog#22654)

Author: nubtron

cloudera/assets/configuration/spec.yaml

@@ -19,6 +19,7 @@ files:
         Console in the `Workload Password`.
       fleet_configurable: true
       required: true
+      secret: true
       value:
         type: string
     - template: init_config/default

mongo/assets/configuration/spec.yaml

@@ -697,6 +697,7 @@ files:
       description: |
         Specify the MongoDB URI, with database to use for reporting (defaults to "admin")
         E.g. mongodb://datadog:LnCbkX4uhpuLHSUrcayEoAZA@localhost:27016/admin
+      secret: true
       value:
         example: mongodb://<USER>:<PASSWORD>@<HOST>:<PORT>/<DB_NAME>
         display_default: null

silverstripe_cms/assets/configuration/spec.yaml

@@ -46,6 +46,7 @@ files:
       fleet_configurable: true
       required: true
       description: "Silverstripe Database Password."
+      secret: true
       value:
         type: string
         example: "<PASSWORD>"