[Transform] Stop transforms at the end of tests

Stopping the transform at the end of test, before the reset, can help
other tests running in parallel.

Resolve elastic#122980

Author: prwhelan

x-pack/plugin/transform/qa/single-node-tests/src/javaRestTest/java/org/elasticsearch/xpack/transform/integration/TransformUpdateIT.java

@@ -340,6 +340,9 @@ private void updateTransferRightsTester(boolean useSecondaryAuthHeaders) throws
             Map<?, ?> transformStatsAsMap = getTransformStateAndStats(transformIdCloned);
             assertThat(XContentMapValues.extractValue("stats.documents_indexed", transformStatsAsMap), equalTo(27));
         }, 15, TimeUnit.SECONDS);
+
+        stopTransform(transformId, BASIC_AUTH_VALUE_TRANSFORM_ADMIN_1, true, false);
+        stopTransform(transformIdCloned, BASIC_AUTH_VALUE_TRANSFORM_ADMIN_1, true, false);
     }
 
     private void deleteUser(String user) throws IOException {