fix: added possibility to revert back to default profile picture (#43962)

* added possibility to revert to default profile picture

* removed required from picture input

* remove addPlaceholderImage and replaced with empty string

* added test for empty string to avatar-renderer

client/src/components/helpers/avatar-renderer.tsx

@@ -33,7 +33,7 @@ function AvatarRenderer({
 
   const isPlaceHolderImage =
     !isPictureValid ||
-    /example.com|identicon.org/.test(picture) ||
+    /example.com|identicon.org|^$/.test(picture) ||
     picture === defaultUserImage;
 
   return (