Revert "Enable NGSA installation (Airflow, AlertMgr and PushGW) by default"

This reverts commit 82afc03ffce54cf3415e91ed077fb2338e2de7e9.

Change-Id: I511d4b9d9c7410999d135d217f33dd96f83e1d84
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/installers/full_install_osm.sh b/installers/full_install_osm.sh
index 7413bd6..426b79c 100755
--- a/installers/full_install_osm.sh
+++ b/installers/full_install_osm.sh
@@ -36,8 +36,7 @@
     echo -e "     -P <VCA pubkey> use VCA/juju public key file"
     echo -e "     -A <VCA apiproxy> use VCA/juju API proxy"
     echo -e "     --pla:          install the PLA module for placement support"
-    echo -e "     --old-sa:       install old Service Assurance framework (MON, POL); do not install Airflow and Pushgateway"
-    echo -e "     --ng-sa:        install new Service Assurance framework (Airflow, AlertManager and Pushgateway)  (enabled by default)"
+    echo -e "     --ng-sa:        install Airflow and Pushgateway to get VNF and NS status (experimental)"
     echo -e "     -m <MODULE>:    install OSM but only rebuild or pull the specified docker images (NG-UI, NBI, LCM, RO, MON, POL, PLA, KAFKA, MONGO, PROMETHEUS, PROMETHEUS-CADVISOR, KEYSTONE-DB, NONE)"
     echo -e "     -o <ADDON>:     ONLY (un)installs one of the addons (k8s_monitor, ng-sa)"
     echo -e "     -O <openrc file path/cloud name>: Install OSM to an OpenStack infrastructure. <openrc file/cloud name> is required. If a <cloud name> is used, the clouds.yaml file should be under ~/.config/openstack/ or /etc/openstack/"
@@ -1005,7 +1004,7 @@
 RELEASE="ReleaseTEN"
 REPOSITORY="stable"
 INSTALL_K8S_MONITOR=""
-INSTALL_NGSA="y"
+INSTALL_NGSA=""
 INSTALL_PLA=""
 INSTALL_VIMEMU=""
 LXD_REPOSITORY_BASE="https://osm-download.etsi.org/repository/osm/lxd"
@@ -1205,7 +1204,6 @@
             [ "${OPTARG}" == "tag" ] && continue
             [ "${OPTARG}" == "registry" ] && continue
             [ "${OPTARG}" == "pla" ] && INSTALL_PLA="y" && continue
-            [ "${OPTARG}" == "old-sa" ] && INSTALL_NGSA="" && continue
             [ "${OPTARG}" == "ng-sa" ] && INSTALL_NGSA="y" && continue
             [ "${OPTARG}" == "volume" ] && OPENSTACK_ATTACH_VOLUME="true" && continue
             [ "${OPTARG}" == "nocachelxdimages" ] && continue