Don't display alt for actor images

We don't need it since it's just a "cosmetic" image

client/src/app/shared/shared-actor-image/actor-avatar.component.html

@@ -1,5 +1,5 @@
 <ng-template #img>
-  <img *ngIf="displayImage()" [class]="classes" [src]="previewImage || avatarUrl || defaultAvatarUrl" [alt]="alt" />
+  <img *ngIf="displayImage()" [class]="classes" [src]="previewImage || avatarUrl || defaultAvatarUrl" alt="" />
 
   <div *ngIf="displayActorInitial()" [ngClass]="classes">
     <span>{{ getActorInitial() }}</span>

client/src/app/shared/shared-actor-image/actor-avatar.component.ts

@@ -43,20 +43,17 @@ export class ActorAvatarComponent implements OnInit, OnChanges {
   }
 
   classes: string[] = []
-  alt: string
   defaultAvatarUrl: string
   avatarUrl: string
 
   ngOnInit () {
     this.buildDefaultAvatarUrl()
 
-    this.buildAlt()
     this.buildAvatarUrl()
     this.buildClasses()
   }
 
   ngOnChanges () {
-    this.buildAlt()
     this.buildAvatarUrl()
     this.buildClasses()
   }
@@ -81,12 +78,6 @@ export class ActorAvatarComponent implements OnInit, OnChanges {
     }
   }
 
-  private buildAlt () {
-    if (this.isAccount()) this.alt = $localize`Account avatar`
-    else if (this.isChannel()) this.alt = $localize`Channel avatar`
-    else this.alt = ''
-  }
-
   private buildDefaultAvatarUrl () {
     this.defaultAvatarUrl = this.isChannel()
       ? VideoChannel.GET_DEFAULT_AVATAR_URL(this.getSizeNumber())