message: Hide "Show tutorials only" button if hacking instructor is disabled
diff: <i class="fa-2x fas fa-trophy" aria-hidden="true"></i> {{"BTN_SHOW_SOLVED" | translate}}
  </mat-button-toggle>
  - <mat-button-toggle id="btnToggleShowOnlyTutorialChallenges" (change)="toggleShowOnlyTutorialChallenges()"
  + <mat-button-toggle id="btnToggleShowOnlyTutorialChallenges" *ngIf="showHackingInstructor" (change)="toggleShowOnlyTutorialChallenges()"
  [checked]="showOnlyTutorialChallenges" [disabled]="restrictToTutorialsFirst && !allTutorialsCompleted"
  [matTooltip]="restrictToTutorialsFirst && !allTutorialsCompleted ? ('INFO_FULL_CHALLENGE_MODE' | translate: {num: challenges.length}) : ''" matTooltipPosition="above">
  <mat-icon>
  