Revert "HBASE-23664 Upgrade JUnit to 4.13 (apache#1010)"

This reverts commit 248d80b.

Author: ndimiduk

pom.xml

@@ -1289,7 +1289,7 @@
     <jetty.jspapi.version>6.1.14</jetty.jspapi.version>
     <jersey.version>1.9</jersey.version>
     <jruby.version>1.6.8</jruby.version>
-    <junit.version>4.13</junit.version>
+    <junit.version>4.12</junit.version>
     <hamcrest.version>1.3</hamcrest.version>
     <htrace.version>3.1.0-incubating</htrace.version>
     <log4j.version>1.2.17</log4j.version>