Perform some minor test cleanup

This standardizes use of annotations/inheritance/formatting across
tests, to make the code more legible and consistent.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=161810734

javatests/google/registry/model/tmch/TmchCrlTest.java

@@ -29,7 +29,6 @@ public class TmchCrlTest {
   @Rule public final AppEngineRule appEngine = AppEngineRule.builder().withDatastore().build();
 
   @Test
-  @SuppressWarnings("null")
   public void testSuccess() throws Exception {
     assertThat(TmchCrl.get()).isNull();
     TmchCrl.set("lolcat", "http://lol.cat");