HBASE-8552: fix coverage org.apache.hadoop.hbase.rest.filter(by Andrey Klochkov)

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.94@1537199 13f79535-47bb-0310-9956-ffa450edef68
HBASE-8557: fix coverage org.apache.hadoop.hbase.rest.metrics(by Aleksey Gorshkov)

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.94@1537213 13f79535-47bb-0310-9956-ffa450edef68