krb5: Silence an error message if no cache entries have ccache stored but renewal is enabled
    
    If no user entries had the ccacheFile attribute, the code would treat
    ENOENT as an error and print a CRIT-level debug message.
    
    Reviewed-by: Alexey Tikhonov <atikhono@redhat.com>
    (cherry picked from commit 22fc051df8bd1a9ec9e22aac85659d1da3bdbaec)