Use method references instead of lambdas when possible

The assertThrows/expectThrows refactoring script does not use method
references, apparently.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=179089048

javatests/google/registry/flows/contact/ContactCheckFlowTest.java

@@ -77,7 +77,7 @@ public class ContactCheckFlowTest
   @Test
   public void testTooManyIds() throws Exception {
     setEppInput("contact_check_51.xml");
-    assertThrows(TooManyResourceChecksException.class, () -> runFlow());
+    assertThrows(TooManyResourceChecksException.class, this::runFlow);
   }
 
   @Test