Disable slm in AbstractWatcherIntegrationTestCase (elastic#50422)

SLM isn't required tests extending from this base class and
only add noise during test suite teardown.

Closes elastic#50302

Author: martijnvg

x-pack/plugin/watcher/src/test/java/org/elasticsearch/xpack/watcher/test/AbstractWatcherIntegrationTestCase.java

@@ -117,6 +117,9 @@ protected Settings nodeSettings(int nodeOrdinal) {
                 .put("xpack.watcher.execution.scroll.size", randomIntBetween(1, 100))
                 .put("xpack.watcher.watch.scroll.size", randomIntBetween(1, 100))
                 .put("index.lifecycle.history_index_enabled", false)
+                // SLM can cause timing issues during testsuite teardown: https://github.com/elastic/elasticsearch/issues/50302
+                // SLM is not required for tests extending from this base class and only add noise.
+                .put("xpack.slm.enabled", false)
                 .build();
     }