L2SS-409: fix shellcheck run_integration_test.sh

sbin/run_integration_test.sh

 #!/bin/bash -e
 
-if [ -z "$LOFA20_DIR"]; then
+if [ -z "$LOFA20_DIR" ]; then
     # We assume we aren't in the PATH, so we can derive our path.
     # We need our parent directory.
     LOFAR20_DIR_RELATIVE=`dirname "$0"`/..