Do we expect a local kamailio to use /var/run/kamailio as it's `run` directory or use `build_folder/run`? if then, then kamailio must be run as `sudo` since it affects root files and folders.

If you do not provide it the default prefix is `/usr/local`, so even if its not installed it will use that when running it, so it must therefore have sudo access and the directory already created (I think).