Change the Guest Agent log_dir to /var/log/trove
Change the Guest Agent log_dir to /var/log/trove

In trove-integration, a patch was submitted to change the value
of the log_dir variable in the trove-guestagent.conf.sample file.
This should be changed here as well so that devstack uses the same
location.

The devstack trove-guestagent.conf file is created by devstack, not
from the sample file, so it needs to be changed here.

(For reference, an actual trove-guestagent.conf file is created by
the cloud provider implementing Trove, who may or may not use the
sample file provided.)

See: https://review.openstack.org/#/c/157973

Change-Id: I41b8e6fe443a2eff376ffc1f92c2ed90c94530b0
mc2014/devstack,wenhuizhang/devstack,varunarya10/devstack,j4/devstack,herrsechs/devstack,vsham20/devstack,avvocatodemarchis/devstack,rushiagr/devstack,openstack-dev/devstack,HPCHub/devstack,samgoon/devstack,CloudServer/devstack,thomasem/devstack,upadhyay-prashant/devstack,ozamiatin/devstack,group-policy/devstack,bljgaurav/openstack-test,avvocatodemarchis/devstack,eharney/devstack,costingalan/devstack,richliu/devstack,pczerkas/devstack,dirkmueller/devstack,bq-xiao/devstack,neerja28/Devstack_GlusterFS,Mahito/devstack,pacinete/devstack,upadhyay-prashant/devstack,eharney/devstack,NaokiMiyata/devstack,NaokiMiyata/devstack,pacinete/devstack,bljgaurav/openstack-test,openstack-dev/devstack,LoHChina/devstack,noironetworks/devstack,atulpatil301/devstack,bswartz/devstack,kplus/devstack-moonshot,varunarya10/devstack,rushiagr/devstack,mssumanth/devstack,nuxeh/devstack,flavio-fernandes/devstack,sc68cal/devstack,liuquansheng47/devstack,BSJAIN92/OpenStack,TwinkleChawla/devstack,mmasaki/devstack,andrewrothstein/devstack,costingalan/devstack,ozamiatin/devstack,andrewrothstein/devstack,Mahito/devstack,parul24/devstack,dtroyer/devstack,nawawi/openstack,parul24/devstack,dtroyer/devstack,wenhuizhang/devstack,nuxeh/devstack,HPCHub/devstack,olivierlemasle/devstack,vsham20/devstack,LoHChina/devstack,sequenceiq/devstack,bigswitch/devstack,prithivm/branch01,flavio-fernandes/devstack,bswartz/devstack,vishnugonela/devstack,j4/devstack,dirkmueller/devstack,liuquansheng47/devstack,mmasaki/devstack,richliu/devstack,pczerkas/devstack,thomasem/devstack,prithivm/branch01,group-policy/devstack,olivierlemasle/devstack,pombredanne/devstack,mc2014/devstack,TwinkleChawla/devstack,CloudServer/devstack,neerja28/Devstack_GlusterFS,sequenceiq/devstack,sc68cal/devstack,herrsechs/devstack,atulpatil301/devstack,bq-xiao/devstack,BSJAIN92/OpenStack,mssumanth/devstack,noironetworks/devstack,vishnugonela/devstack,kplus/devstack-moonshot,pombredanne/devstack,bigswitch/devstack,samgoon/devstack,nawawi/openstack