[TEST] Fix exception specification

Caused by a clash between two PRs

Original commit: elastic/x-pack-elasticsearch@47910636eb

qa/smoke-test-ml-with-security/src/test/java/org/elasticsearch/smoketest/MlWithSecurityIT.java

@@ -37,7 +37,7 @@ public class MlWithSecurityIT extends ESClientYamlSuiteTestCase {
     private static final String TEST_ADMIN_PASSWORD = "changeme";
 
     @After
-    public void clearMlState() throws IOException {
+    public void clearMlState() throws Exception {
         new MlRestTestStateCleaner(logger, adminClient(), this).clearMlMetadata();
     }