docs: consistent spacing in tutorial html files (#23105) (#24497)

- Removed surrounding spaces in interpolation expressions following the styleguide
- Consistant spacing of two spaces in html

Fixes #23105

PR Close #24497

aio/content/examples/toh-pt6/src/app/hero-detail/hero-detail.component.html

@@ -1,5 +1,5 @@
 <div *ngIf="hero">
-  <h2>{{ hero.name | uppercase }} Details</h2>
+  <h2>{{hero.name | uppercase}} Details</h2>
   <div><span>id: </span>{{hero.id}}</div>
   <div>
     <label>name:

aio/content/examples/toh-pt6/src/app/heroes/heroes.component.html

@@ -20,7 +20,7 @@
     </a>
     <!-- #docregion delete -->
     <button class="delete" title="delete hero"
-    (click)="delete(hero)">x</button>
+      (click)="delete(hero)">x</button>
     <!-- #enddocregion delete -->
   </li>
 </ul>