TT#126250 apply: fix error when called with no arguments

introduced at commit eff9d4ae07

> ngcp-service: info: Action restart skipped, service kamailio-proxy is not for this role
> 2021-08-17 14:59:18 lb01a: Synchronizing current with expected services state
> /usr/share/ngcp-ngcpcfg/scripts//apply: line 56: $1: unbound variable

Change-Id: I75a551327ecb42b7ff6a14a5206b85fb35e5f608

scripts/apply

@@ -53,7 +53,7 @@ fi
 
 "${SCRIPTS}"/build "${build_args[@]}" "${check_args[@]}"
 "${SCRIPTS}"/services "${services_args[@]}"
-"${SCRIPTS}"/commit "$1"
+"${SCRIPTS}"/commit "${1:-}"
 
 # We "commit" AFTER we "build", therefore the state information is out of date
 # and would be marked as "dirty". As we have full control over this during the