Fix copy-hdfs-jars-to-maven.sh to unbreak Jenkins HBase builds

Summary:
Apparently the COMMANDER_WORKSPACE variable is not set in the Jenkins
environment, so using the username to determine whether we are running
as part of a Jenkins build.

Simple change, not reviewed.

Test Plan:
Tested on a build server.

copy-hdfs-jars-to-maven.sh

@@ -50,7 +50,7 @@ echo "** HBase builds will  pick up the HDFS* jars from the local maven repo."
 # the localRepository for a central mvn repo that can be shared between
 # all of the build/test agents
 OPTS=""
-if [ -n "${COMMANDER_WORKSPACE:-}" ];then
+if [[ -n "${COMMANDER_WORKSPACE:-}" || "$USER" == "svcscm" ]]; then
     OPTS="-s /scm/git/electric/hadoop_builds/settings.xml"
 fi