fix expected error message in clear-retention test

assert_throws_async does strict equality on the message. The actual
S3 error mapped from OBJECT_LOCKED is AccessDeniedObjectLocked which
has message 'Access Denied because object protected by object lock.'
not the generic 'Access Denied'.

Signed-off-by: kajalpareek-lab <pareekkajal97@gmail.com>

Author: kajalpareek-lab

src/test/integration_tests/api/s3/test_s3_worm.js

@@ -591,7 +591,7 @@ mocha.describe('s3 worm', function() {
                 Key: CLEAR_RET_KEY,
                 VersionId: clear_ret_version_id,
                 Retention: {},
-            }), 'AccessDenied', 'Access Denied');
+            }), 'AccessDenied', 'Access Denied because object protected by object lock.');
         });
 
         mocha.it('should clear GOVERNANCE retention with bypass flag', async function() {