BUILD: Enables venv for building

Requires the update from dockerfiles to enable venv, and will use the
environment created at build time of the container when running builds.

Change-Id: I94a3f4a4d4691506ba524c4cd8383fcb8f260cea
Signed-off-by: Matthew Dalzell <matthew.dalzell@arm.com>
diff --git a/src/org/trustedfirmware/Gerrit.groovy b/src/org/trustedfirmware/Gerrit.groovy
index 989b7fe..bbfd743 100644
--- a/src/org/trustedfirmware/Gerrit.groovy
+++ b/src/org/trustedfirmware/Gerrit.groovy
@@ -38,10 +38,7 @@
     echo Not running for a Gerrit change, skipping vote.
     exit 0
   fi
-  if [ ! -d venv ] ; then
-    virtualenv -p \$(which python3) venv
-  fi
-  . venv/bin/activate
+  . /.venv/bin/activate
   pip -q install requests
   ./tf-m-ci-scripts/jenkins/verify.py --category ${category} --value ${value} --verify-name ${verify_name} --user \$VERIFY_USER
   """)
@@ -65,10 +62,7 @@
     echo Not running for a Gerrit change, skipping.
     exit 0
   fi
-  if [ ! -d venv ] ; then
-    virtualenv -p \$(which python3) venv
-  fi
-  . venv/bin/activate
+  . /.venv/bin/activate
   pip -q install requests
   ./tf-m-ci-scripts/jenkins/comment.py --comment "${comment}" --user \$GERRIT_USER
   """)