[web] Update links to Koji builds should not use koji search

[juhp]

It should be possible for Bodhi to know the exact koji build corresponding to an NVR (since they must be unique).

eg https://bodhi.fedoraproject.org/updates/FEDORA-2023-1be0af64c4 has a build link:
https://koji.fedoraproject.org/koji/search?terms=distrobox-1.6.0.1-1.fc39&type=build&match=exact
which should be simplified to just https://koji.fedoraproject.org/koji/buildinfo?buildID=2322876
(it is just a simple Koji API call to get the buildid corresponding to an NVR).

Opening the direct link is noticeably faster for me: in fact I deliberately don't open Bodhi build links because of this...

[mattiaverga]

This is rather tricky: we have Build.get_build_id(), but it needs to query Koji, thus may slow down page generation.
I'm postponing after 8.0 release to look into that. Maybe we can just store the build id in database, if it is handy for other tasks too.