fix(deck): Set unchecked behavior (#8117) (#8140)

Co-authored-by: Kevin Woo <kevinawoo@gmail.com>
(cherry picked from commit dc4c4c3)

Co-authored-by: Justin Lee <justin.r.lee@gmail.com>

app/scripts/modules/core/src/pipeline/config/stages/failOnFailedExpressions/failOnFailedExpressions.directive.html

@@ -3,7 +3,7 @@
     <div class="col-md-8 col-md-offset-1">
       <div class="checkbox pull-left">
         <label>
-          <input type="checkbox" ng-false-value="undefined" ng-model="$ctrl.stage.failOnFailedExpressions" />
+          <input type="checkbox" ng-false-value="false" ng-model="$ctrl.stage.failOnFailedExpressions" />
           <strong
             >Fail stage on failed
             <a href="http://spinnaker.github.io/guides/user/pipeline-expressions" target="_blank">expressions</a>