account-page-local: Properly check if the entry has focus

Since long time (e.g. GTK4 beginnings [1]) the GtkEntry's are never
focused while their GtkText child is, so check for that other than the
entry focus itself (that shouldn't ever happen, but kept for clarity).

This restore the logic for avoiding changing the user once it has
been customized.

[1] https://blog.gtk.org/2019/03/15/entries-in-gtk-4/

(cherry picked from commit e20814cc)