Migrate to Flogger (yellow)

This is a 'yellow' Flogger migration CL. Yellow CLs should be mostly safe
but include changes that are notable for one reason or another. Manual
intervention may be required to address small issues.

The comments in this CL indicate cases where suggested code changes
should be double checked, or even modified. There may even be cases where
files outside this CL are affected by changes to things such as logger
visibility. However if a change does not have an associated comment then
it should be safe.

For more information, see []
Base CL: 197826149

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=198097990

javatests/google/registry/keyring/api/ComparatorKeyringTest.java

@@ -21,6 +21,7 @@ import static java.nio.charset.StandardCharsets.UTF_8;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
+import com.google.common.flogger.LoggerConfig;
 import com.google.common.testing.TestLogHandler;
 import java.io.IOException;
 import java.util.logging.Level;
@@ -80,12 +81,12 @@ public class ComparatorKeyringTest {
 
   @Before
   public void setUp() {
-    ComparatorKeyring.logger.getFormattingLogger().addHandler(testLogHandler);
+    LoggerConfig.getConfig(ComparatorKeyring.class).addHandler(testLogHandler);
   }
 
   @After
   public void tearDown() {
-    ComparatorKeyring.logger.getFormattingLogger().removeHandler(testLogHandler);
+    LoggerConfig.getConfig(ComparatorKeyring.class).removeHandler(testLogHandler);
   }
 
   @Test