fix: [compose-core] add missing ``RELATION_DATA_FILE`` var for indirect action

bin/compose-core

@@ -3608,6 +3608,7 @@ _run_service_action_relation() {
         print_syntax_error "$FUNCNAME: too many arguments in action descriptor"
         return 1
     fi
+    RELATION_DATA_FILE=$(get_relation_data_file "$service" "$target_service" "$relation_name" "$relation_config") || return 1
 
     export action_errlvl_file="$state_tmpdir/action-$service-$charm-$action-errlvl"
     export state_tmpdir
@@ -3619,6 +3620,7 @@ _run_service_action_relation() {
         export RELATION_TARGET_CHARM="$target_charm"
         export RELATION_BASE_SERVICE="$service"
         export RELATION_BASE_CHARM="$charm"
+        export RELATION_DATA_FILE="$RELATION_DATA_FILE"
         export ACTION_NAME=$action
         export ACTION_SCRIPT_PATH="$action_script_path"
         export CONTAINER_NAME=$(get_top_master_service_for_service "$service")