dist: debian: fix detection of debuild
dist: debian: fix detection of debuild

We detect if debuild is already installed, in order to avoid
re-installing it, which can fail due to flakey mirrors. However,
we use the wrong path to detect if it is installed, so we do in fact
fail on flakey Fedora mirrors.

Fix by using the correct path.

Reviewed-by: Takuya ASADA <4ebfb6f510af412d6e89fefa3ab96d9c8b5e3fff@scylladb.com>

scylladb/scylla-tools-java,scylladb/scylla-tools-java,scylladb/scylla-tools-java,scylladb/scylla-tools-java