krb5: accept changed principal if krb5_canonicalize=True
    
    Currently SSSD accepts significant changes in the principal only if
    krb5_use_enterprise_principal=True. But canonicalization can lead to
    similar changes so they should be accepted in this case as well.
    
    Resolves:
    https://pagure.io/SSSD/sssd/issue/3408
    
    Reviewed-by: Robbie Harwood <rharwood@redhat.com>
    (cherry picked from commit ca95807a9060e454ee68f6f30558d6f7ee968c39)