message: make message only visible when challenges shown
diff: <i class="fa-2x fas fa-exclamation-circle" aria-hidden="true"></i> {{"BTN_SHOW_DISABLED" | translate}}
  </mat-button-toggle>
  - <div *ngIf="challengesDisabled" class="disabled-challenges-infoBox mat-button">
  + <div *ngIf="showDisabledChallenges" class="disabled-challenges-infoBox mat-button">
  {{"INFO_DISABLED_CHALLENGES" | translate}} <a href='https://pwning.owasp-juice.shop/part1/challenges.html#potentially-dangerous-challenges'>security reasons!</a>
  </div>
  