[webui] Do not override JS method in multiple requests

`function update_rpmlint_result` and `function update_build_result`
where defined more than once for multiple request.

This fixes the broken "Selecting build / rpmlint result" in request
show page, reported in
https://github.com/openSUSE/open-build-service/pull/4720

Co-authored-by: Christian Bruckmayer <cbruckmayer@suse.com>