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/rde/imports/RdeImportUtilsTest.java

@@ -297,7 +297,6 @@ public class RdeImportUtilsTest extends ShardableTestCase {
 
   /** Verifies that no errors are thrown when a valid escrow file is validated */
   @Test
-  @SuppressWarnings("CheckReturnValue")
   public void testValidateEscrowFile_valid() throws Exception {
     xmlInput = DEPOSIT_XML.openBufferedStream();
     when(gcsUtils.openInputStream(any(GcsFilename.class))).thenReturn(xmlInput);