logs: don’t warn for lock file maintenance lerna

lib/manager/npm/post-update/index.js

@@ -604,11 +604,18 @@ async function getAdditionalFiles(config, packageFiles) {
               logger.trace('File is unchanged');
             }
           } catch (err) {
+            if (config.updateType === 'lockFileMaintenance') {
+              logger.info(
+                { lockFilePath },
+                'No lock file found after lerna bootstrap'
+              );
+            } else {
               logger.warn(
                 { lockFilePath },
                 'No lock file found after lerna bootstrap'
               );
             }
+          }
         } else {
           logger.trace('No lock file found');
         }