Tests: Fix Typo Causing Flaky Settings Test (elastic#32665)

* We were comparing the wrong timeout value in the `randomValueOtherThan` call here, leading to no mutation happening for a certain seed
* closes elastic#32639

Author: original-brownbear

server/src/test/java/org/elasticsearch/action/admin/indices/settings/put/UpdateSettingsRequestStreamableTests.java

@@ -41,7 +41,7 @@ protected UpdateSettingsRequest mutateInstance(UpdateSettingsRequest request) {
         List<Runnable> mutators = new ArrayList<>();
         mutators.add(() -> mutation
                 .masterNodeTimeout(randomValueOtherThan(request.masterNodeTimeout().getStringRep(), ESTestCase::randomTimeValue)));
-        mutators.add(() -> mutation.timeout(randomValueOtherThan(request.masterNodeTimeout().getStringRep(), ESTestCase::randomTimeValue)));
+        mutators.add(() -> mutation.timeout(randomValueOtherThan(request.timeout().getStringRep(), ESTestCase::randomTimeValue)));
         mutators.add(() -> mutation.settings(mutateSettings(request.settings())));
         mutators.add(() -> mutation.indices(mutateIndices(request.indices())));
         mutators.add(() -> mutation.indicesOptions(randomValueOtherThan(request.indicesOptions(),