UTIL: Sanitize newline and carriage return characters.
    
    Introducing valid usernames with a trailing newline character triggers
    the removal of valid LDB cache entries.
    
    Resolves:
    https://pagure.io/SSSD/sssd/issue/3317
    
    Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>
    (cherry picked from commit ee2906c1d50ab8001863b0a423fe957d4e0bcb37)