Use consistent value for checkPermissions in merger

Use consistent value for checkPermissions in merger

We recently added a permission check when retrieving metadata here
https://github.com/civicrm/civicrm-core/commit/0e88731ff38f4bcf5a4d53c7e2ced01f70533ff1#diff-fe60c89ebe94bbd40114d135459371cc53708db1f2952ade6c0ce9b3468c4dabR2306

However, when that function is called from getFieldValueAndLabel that is not being passed
and is defaulting to TRUE. This is causing issues in a cron context where
checkPermissions is being used (well actually in a unit test in our custom code
simulating that possiblility)