ENGCOM-1187: [Forwardport] Disable 'Back' button on the first step of the setup #14460

 - Merge Pull Request #14460 from mastiuhin-olexandr/magento2:2.3-develop-PR-port-14309
 - Merged commits:
   1. 14f5227
   2. 1214c4f

Author: magento-engcom-team

setup/pub/magento/setup/main.js

@@ -93,10 +93,6 @@ main.controller('navigationController',
             return str.indexOf(suffix, str.length - suffix.length) !== -1;
         };
 
-        $scope.goToStart = function() {
-            $scope.goToAction($state.current.type);
-        };
-
         $scope.goToBackup = function() {
             $state.go('root.create-backup-uninstall');
         };

setup/view/magento/setup/readiness-check.phtml

@@ -18,7 +18,7 @@
             <button
                 type="button"
                 class="btn"
-                ng-click="goToStart()"
+                disabled="disabled"
                 >Back</button>
         </div>
         <div class="btn-wrap btn-wrap-try-again"