Don't fail if optional RPM macros file is missing
    
    With fix for https://pagure.io/freeipa/issue/7951 we started to modify
    RPM macros in Azure CI environment. Don't fail if the file does not
    exist anymore like it happens now in Fedora.
    
    Fixes: https://pagure.io/freeipa/issue/9347
    
    Signed-off-by: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Francisco Trivino <ftrivino@redhat.com>