Fixed errcheck issues in server/channels/api4/license_local.go (#28558)

Co-authored-by: Ben Schumacher <ben.schumacher@mattermost.com>

server/i18n/en.json

@@ -2234,7 +2234,7 @@
   },
   {
     "id": "api.license.add_license.copy.app_error",
-    "translation": "Failed to copy license."
+    "translation": "Failed to copy license file content to buffer"
   },
   {
     "id": "api.license.add_license.expired.app_error",