Update metadata.yaml for azure eventhubs binding (#3837)

Signed-off-by: Oisin Grehan <oising@gmail.com>

Author: oising

bindings/azure/eventhubs/metadata.yaml

@@ -162,8 +162,9 @@ metadata:
       Storage container name.
     example: '"myeventhubstoragecontainer"'
   - name: getAllMessageProperties
+    type: bool
     required: false
-    default: "false"
+    default: false
     example: "false"
     binding:
       input: true