Exploratory testing
Create a competency framework or use an existing one.
In that framework, create a competency and other competencies child of that parent competency.
Select the parent competency and click Edit link.
Click "Competency rule" on the menu
Make sure Competency rule works as expected after the attribute removed.
Grep for ng-label, make sure it's not used anywhere.
jpataleta spotted the attribute ng-label on competency_rule_config.mustache while reviewing MDL-57770.
That attribute is useless, probably a bad copy and paste and can be removed to avoid confusion.