refactor(schema): consolidate unnecessary conditionals in map toJSONSchema

Re: #15184

Author: vkarpov15

lib/schema/map.js

@@ -91,14 +91,7 @@ class SchemaMap extends SchemaType {
 
     const isRequired = this.options.required && typeof this.options.required !== 'function';
     const result = createJSONSchemaTypeDefinition('object', 'object', useBsonType, isRequired);
-
-    if (embeddedSchemaType.schema) {
-      result.additionalProperties = useBsonType
-        ? { ...embeddedSchemaType.toJSONSchema(options) }
-        : { ...embeddedSchemaType.toJSONSchema(options) };
-    } else {
-      result.additionalProperties = embeddedSchemaType.toJSONSchema(options);
-    }
+    result.additionalProperties = embeddedSchemaType.toJSONSchema(options);
 
     return result;
   }