Remove SCREEN_LOGDIR from devstack

SCREEN_LOGDIR has already been deprecated [1]. We should
remove it.

[1] https://review.openstack.org/#/c/499186

Change-Id: I2922816fb6372e38c121e4287f055087826ae192

devstack/local-gbp.conf

@@ -25,7 +25,6 @@ SERVICE_TOKEN=abc123
 
 LOG_COLOR=False
 DEST=/opt/stack/new
-SCREEN_LOGDIR=$DEST/logs/screen
 LOGFILE=$DEST/logs/stack.sh.log
 
 SKIP_EXERCISES=volumes,trove,swift,sahara,euca,bundle,boot_from_volume,aggregates,zaqar,client-env,client-args,sec_groups,neutron-adv-test,floating_ips,horizon

devstack/local.conf.nfp

@@ -5,7 +5,6 @@ DEST=/opt/stack
 LOGFILE=$DEST/logs/stack.sh.log
 VERBOSE=True
 LOG_COLOR=False
-SCREEN_LOGDIR=$DEST/logs/screen
 
 # Credentials
 ADMIN_PASSWORD=mysecret

gbpservice/tests/contrib/devstack/local-aim.conf

@@ -8,7 +8,6 @@ SERVICE_TOKEN=abc123
 
 LOG_COLOR=False
 DEST=/opt/stack/new
-SCREEN_LOGDIR=$DEST/logs/screen
 LOGFILE=$DEST/logs/stack.sh.log
 SKIP_EXERCISES=volumes,trove,swift,sahara,euca,bundle,boot_from_volume,aggregates,zaqar,client-env,client-args,sec_groups,neutron-adv-test,floating_ips,horizon
 

gbpservice/tests/contrib/devstack/local-nfp.conf

@@ -65,7 +65,6 @@ enable_service orchestrator,proxy,proxy_agent,base_configurator,q-lbaasv2-agent
 
 LOG_COLOR=False
 DEST=/opt/stack/new
-SCREEN_LOGDIR=$DEST/logs/screen
 LOGFILE=$DEST/logs/stack.sh.log
 SKIP_EXERCISES=volumes,trove,swift,sahara,euca,bundle,boot_from_volume,aggregates,zaqar,client-env,client-args,sec_groups,neutron-adv-test,floating_ips,horizon
 

gbpservice/tests/contrib/devstack/local.conf

@@ -57,7 +57,6 @@ ENABLED_SERVICES+=,heat,h-api,h-api-cfn,h-api-cw,h-eng
 
 LOG_COLOR=False
 DEST=/opt/stack/new
-SCREEN_LOGDIR=$DEST/logs/screen
 LOGFILE=$DEST/logs/stack.sh.log
 SKIP_EXERCISES=volumes,trove,swift,sahara,euca,bundle,boot_from_volume,aggregates,zaqar,client-env,client-args,sec_groups,neutron-adv-test,floating_ips,horizon