grafana: [skip-ci] Fix syntax error that was causing entrypoint failure

This was just a bash scripting syntax error which prevented the demo
script from working because the "docker compose up --wait" could not
succeed.

Change-Id: I7912a3373f44626d68ce8a9a95a9b8f2b91c3576

build/docker/grafana/config-then-run.sh

@@ -19,7 +19,7 @@ RE='(.+):\/\/([^:@]*)(:([^@]*))?@([^:\/]+)(:[0-9]+)?(\/(.+))?'
 # Only parse if UPSTREAM_DB_URL is not empty.
 # Otherwise, these parameters must be passed down from the environment.
 # TODO: Remove UPSTREAM_DB_URL completely when new docker images are in ECR
-if [[! -z "${UPSTREAM_DB_URL}" ]; then
+if [[ -n "${UPSTREAM_DB_URL}" ]]; then
     [[ $UPSTREAM_DB_URL =~ $RE ]]
     RS_DB_TYPE=${BASH_REMATCH[1]}
     RS_USER=${BASH_REMATCH[2]}