[AETHER-421] Enabling onos build

CI/CD jobs will build locally a new onos image from onos-2.2
using the "tost" profile. This image tagged as "tost-onos" will be
used as initial stage for "tost" image.

Deprecate tost-onos:2.2-latest

Do not activate apps during the build process

Change-Id: I8efb93f3c99344822c74f277c52bba8adbc61dba
diff --git a/Dockerfile.tost b/Dockerfile.tost
index e191a9d..c4ecc44 100644
--- a/Dockerfile.tost
+++ b/Dockerfile.tost
@@ -16,7 +16,7 @@
 
 # We start from an onos image and install the apps.
 # We need at least an onos image built with 'tost' profile
-FROM onosproject/tost-onos:2.2-latest as install
+FROM tost-onos as install
 
 ARG KARAF_VERSION
 ARG LOCAL_APPS
@@ -45,7 +45,7 @@
 RUN ./app-install.sh
 
 # Create the final image coping over the installed applications from the install stage
-FROM onosproject/tost-onos:2.2-latest
+FROM tost-onos
 
 ARG KARAF_VERSION