Fix failing evil logging configuration tests

This commit fixes failing evil logging configuration tests. The test for
resolving multiple configuration files was failing after
9a58fc2348 removed some of the
configuration needed for this test. The solution is revert the removal
of that configuration, but remove additivity from the test logger to
prevent the evil logger tests from failing.

qa/evil-tests/src/test/resources/org/elasticsearch/common/logging/config/log4j2.properties

@@ -17,6 +17,9 @@ rootLogger.appenderRef.file.ref = file
 
 logger.test.name = test
 logger.test.level = trace
+logger.test.appenderRef.console.ref = console
+logger.test.appenderRef.file.ref = file
+logger.test.additivity = false
 
 appender.deprecation_file.type = File
 appender.deprecation_file.name = deprecation_file