Longer RCS suite timeout due to slow keystore (elastic#117157)

Rather than muting the suite and losing signal, bump the suite timeout to account for very slow keystore operations.

We should follow this up with performance improvements around keystore setup in tests.

Closes: elastic#116883

x-pack/plugin/security/qa/multi-cluster/src/javaRestTest/java/org/elasticsearch/xpack/remotecluster/RemoteClusterSecurityReloadCredentialsRestIT.java

@@ -42,7 +42,7 @@
 import static org.hamcrest.Matchers.nullValue;
 
 // account for slow stored secure settings updates (involves removing and re-creating the keystore)
-@TimeoutSuite(millis = 10 * TimeUnits.MINUTE)
+@TimeoutSuite(millis = 20 * TimeUnits.MINUTE)
 public class RemoteClusterSecurityReloadCredentialsRestIT extends AbstractRemoteClusterSecurityTestCase {
 
     private static final MutableSettingsProvider keystoreSettings = new MutableSettingsProvider();