file-header: Remove unnecessary RuleWalker (#2469)
file-header: Remove unnecessary RuleWalker (#2469)


mprobst/tslint,palantir/tslint,JoshuaKGoldberg/tslint,RyanCavanaugh/tslint,IllusionMH/tslint,palantir/tslint,berickson1/tslint,RyanCavanaugh/tslint,palantir/tslint,andy-hanson/tslint,IllusionMH/tslint,andy-hanson/tslint,andy-ms/tslint,berickson1/tslint,JoshuaKGoldberg/tslint,andy-hanson/tslint,berickson1/tslint,mprobst/tslint,JoshuaKGoldberg/tslint,andy-ms/tslint,IllusionMH/tslint,RyanCavanaugh/tslint,mprobst/tslint,andy-ms/tslint