do not redefine path in elasticsearch
do not redefine path in elasticsearch

in I0272d56bc2e50e8174db78bd449f65f60f7f4000, we reset DEST value
when installing elasticsearch. it gets set to /opt/stack/ which is
not always correct in gate causing the path to be wrong and
elasticseach cannot be installed. we should reuse DEST from stackrc

Change-Id: Ia3a2383ada30c4e92c37386aedd6164c69cac60a
Closes-Bug: #1484182

samgoon/devstack,pczerkas/devstack,costingalan/devstack,olivierlemasle/devstack,dtroyer/devstack,eharney/devstack,eharney/devstack,mc2014/devstack,atulpatil301/devstack,nawawi/openstack,olivierlemasle/devstack,TwinkleChawla/devstack,richliu/devstack,mssumanth/devstack,prithivm/branch01,varunarya10/devstack,Mahito/devstack,atulpatil301/devstack,richliu/devstack,dtroyer/devstack,noironetworks/devstack,ozamiatin/devstack,avvocatodemarchis/devstack,ozamiatin/devstack,dirkmueller/devstack,prithivm/branch01,dirkmueller/devstack,vsham20/devstack,noironetworks/devstack,thomasem/devstack,Mahito/devstack,vsham20/devstack,pombredanne/devstack,parul24/devstack,parul24/devstack,openstack-dev/devstack,bigswitch/devstack,group-policy/devstack,avvocatodemarchis/devstack,TwinkleChawla/devstack,samgoon/devstack,pombredanne/devstack,openstack-dev/devstack,mssumanth/devstack,mc2014/devstack,bswartz/devstack,nawawi/openstack,pczerkas/devstack,thomasem/devstack,costingalan/devstack,bigswitch/devstack,bswartz/devstack,varunarya10/devstack,group-policy/devstack