[Glitch] Add limit of 8 different reaction types per announcement

Port f816da9c64 to glitch-soc

Signed-off-by: Thibaut Girka <thib@sitedethib.com>

app/javascript/flavours/glitch/features/getting_started/components/announcements.js

@@ -265,7 +265,7 @@ class ReactionsBar extends ImmutablePureComponent {
           />
         ))}
 
-        <EmojiPickerDropdown onPickEmoji={this.handleEmojiPick} button={<Icon id='plus' />} />
+        {visibleReactions.size < 8 && <EmojiPickerDropdown onPickEmoji={this.handleEmojiPick} button={<Icon id='plus' />} />}
       </div>
     );
   }