Revert "LDAP/IPA: add local email address to aliases"
    
    This reverts commit 9a310913d696d190db14c625080678db853a33fd.
    
    Storing the e-mail address as a nameAlias was a performance optimization
    to avoid having to fall back to the UPN lookup, but had the disadvantage
    of returning multiple results for cases where an e-mail address is the
    same as a user's fully qualified name.
    
    Since the e-mail lookups would still work without this optimization,
    just after one more lookup, let's revert the patch.
    
    Resolves:
    https://pagure.io/SSSD/sssd/issue/3607
    
    Reviewed-by: Fabiano Fidêncio <fidencio@redhat.com>