L2SS-225: Move set +e after the check for docker compose

The reason is simple.  When I check for docker-compose, the
execution can fail.  Then I'll check for the built-in
docker compose.  If set -e is active the first failure will result
the script being aborted with no chance to check for the second
option.

bootstrap/sbin/rebuild_system_from_scratch.sh

 #! /usr/bin/env bash
 
-set -e
-
 HOME_DIR=${LOFAR20_DIR:-${PWD}}
 if [ ! -d ${HOME_DIR}/bootstrap ]; then
     # HOME_DIR/bootstrap needs to exist for this script to work.
@@ -25,6 +23,9 @@ else
     return 1
 fi
 
+# Any error should terminate this script.
+set -e
+
 # Save for the moment when tango will be cloned.
 OLD_HOME_DIR=${HOME_DIR}.old