[solr] tune down log output during tests.

solr/src/test/resources/log4j.properties

+# Copyright (c) 2015-2016 YCSB contributors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you
+# may not use this file except in compliance with the License. You
+# may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied. See the License for the specific language governing
+# permissions and limitations under the License. See accompanying
+# LICENSE file.
+#
+
+# Root logger option
+log4j.rootLogger=INFO, stderr
+
+log4j.appender.stderr=org.apache.log4j.ConsoleAppender
+log4j.appender.stderr.target=System.err
+log4j.appender.stderr.layout=org.apache.log4j.PatternLayout
+log4j.appender.stderr.layout.conversionPattern=%d{yyyy/MM/dd HH:mm:ss} %-5p %c %x - %m%n
+
+# Suppress messages from ZooKeeper
+log4j.logger.org.apache.zookeeper=ERROR
+# Solr classes are too chatty in test at INFO
+log4j.logger.org.apache.solr=ERROR
+log4j.logger.org.eclipse.jetty=ERROR