KCM: Deleting a non-existent ccache should not yield an error
    
    Resolves:
    https://pagure.io/SSSD/sssd/issue/3910
    
    When the KCM destroy operation is called, it receives a name as an input. If
    the name cannot be found, we would currently return KRB5_CC_NOTFOUND. But
    other ccache types return KRB5_FCC_NOFILE in that case and e.g. utilities
    like kdestroy special case KRB5_FCC_NOFILE to be non-fatal.
    
    Reviewed-by: Tomas Halman <thalman@redhat.com>