Run search reindex automatically when field is marked "This field's contents are indexed and can be searched"

Currently, If you create a text field and enter some content, then mark that field as "This field's contents are indexed and can be searched", content entered prior to flagging the field as searchable is not found by the search. The feature request is to ran search reindex every time the searchable field is toggled on. For future reference, the feature request id is CR-454559.