LU-17128 build: fix lnet.service missing issue on Ubuntu 22.04

LU-17128 build: fix lnet.service missing issue on Ubuntu 22.04

The lnet.service file was in the lustre-client-utils package
built on Ubuntu 20.04, but it was missing from the package
built on Ubuntu 22.04.

This is caused by the dpkg-buildpackage change introduced by
dpkg version 1.21.1ubuntu2.1 installed by default on Ubuntu 22.04.
To fix this issue, we need to specify build profiles explicitly
to dpkg-buildpackage via -P|--build-profiles option instead of
just setting the environment variable DEB_BUILD_PROFILES.

Test-Parameters: trivial clientdistro=ubuntu2204

Signed-off-by: Jian Yu <yujian@whamcloud.com>
Change-Id: I9975ef357f0aba722c56d27eaa9b2cfbccc9c524