Fix schema error after logout (#19933)

Detailed explanation:

The schema failure is due to utils.image-server/get-initials-avatar-uri being
called with a nil profile customization color right after the user confirms
logout.

Right after logging out, the subscription :profile/profile-with-image is
recomputed. One of its signal inputs is :profile/profile. Right after logout,
the output of sub :profile/profile is always nil (this is correct, nobody is
logged in). This means that the sub :profile/profile-with-image will try to
calculate the multiaccount URI by passing a nil profile. This is wasteful
computation and is also the cause of the schema for
utils.image-server/get-initials-avatar-uri to fail, because it expects the
profile's customization-color to be present.

src/status_im/subs/profile.cljs

@@ -279,7 +279,12 @@
  :<- [:initials-avatar-font-file]
  :<- [:theme]
  (fn [[profile ens-names port font-file theme] [_ avatar-opts]]
- (replace-multiaccount-image-uri profile ens-names port font-file avatar-opts theme)))
+ ;; Right after logout, this subscription is recomputed, but the sub
+ ;; `:profile/profile` output will always be nil. We skip any further
+ ;; processing because it's wasteful and because it will trigger a schema
+ ;; error.
+ (when profile
+ (replace-multiaccount-image-uri profile ens-names port font-file avatar-opts theme))))
 
 (re-frame/reg-sub
  :profile/image