Fix mismatch in types of Predicates being used

We're going to need to switch away from Guava's Functions and Predicates for
everything and replace them with the java.util versions. Unfortunately there
does not appear to be an automated tool to do this all at once. Refaster got
close but doesn't seem to care about these particular types of mismatch (I
suspect we're using a different version of the JDK than the outside world;
ours is OK with Guava classes).

This also bumps up Guava to 0.23, which is needed for some new functionality
used in combination with Java 8 features.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=170531539

javatests/google/registry/server/TestServer.java

@@ -18,6 +18,7 @@ import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Throwables.throwIfUnchecked;
 import static com.google.common.util.concurrent.Runnables.doNothing;
 import static google.registry.util.NetworkUtils.getCanonicalHostName;
+import static java.util.concurrent.Executors.newCachedThreadPool;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
@@ -128,14 +129,18 @@ public final class TestServer {
   /** Stops the HTTP server. */
   public void stop() {
     try {
-      new SimpleTimeLimiter().callWithTimeout(new Callable<Void>() {
-        @Nullable
-        @Override
-        public Void call() throws Exception {
-          server.stop();
-          return null;
-        }
-      }, SHUTDOWN_TIMEOUT_MS, TimeUnit.MILLISECONDS, true);
+      SimpleTimeLimiter.create(newCachedThreadPool())
+          .callWithTimeout(
+              new Callable<Void>() {
+                @Nullable
+                @Override
+                public Void call() throws Exception {
+                  server.stop();
+                  return null;
+                }
+              },
+              SHUTDOWN_TIMEOUT_MS,
+              TimeUnit.MILLISECONDS);
     } catch (Exception e) {
       throwIfUnchecked(e);
       throw new RuntimeException(e);