logs: don’t log lockFileMaintenance missing display

lib/workers/repository/updates/generate.js

@@ -93,8 +93,11 @@ function generateBranchConfig(branchUpgrades) {
       }
     }
 
-    if (upgrade.displayFrom.length * upgrade.displayTo.length === 0) {
-      logger.info({ upgrade }, 'empty displayFrom/displayTo');
+    if (
+      upgrade.upgradeType !== 'lockFileMaintenance' &&
+      upgrade.displayFrom.length * upgrade.displayTo.length === 0
+    ) {
+      logger.info({ config: upgrade }, 'empty displayFrom/displayTo');
     }
     if (upgrade.depName) {
       upgrade.depNameEscaped = (upgrade.lookupName || upgrade.depName).replace(