Fix avatar defects (#11473)

* Fix avatar initial centering in pills for bubbles

* Express user info avatar size in pixes

* fix link pill icon

* Fix snapshot test

res/css/views/elements/_Pill.pcss

@@ -80,6 +80,7 @@ limitations under the License.
         height: 16px;
         padding: 1px;
         width: 16px;
+        border-radius: 50%;
     }
 
     .mx_Pill_UserIcon {

res/css/views/rooms/_EventBubbleTile.pcss

@@ -415,11 +415,6 @@ limitations under the License.
         }
     }
 
-    .mx_BaseAvatar,
-    .mx_EventTile_avatar {
-        line-height: 1;
-    }
-
     &[data-has-reply="true"] {
         > .mx_EventTile_line {
             flex-direction: column;