autopkgtest: clean up dependencies of boot-smoke test

autopkgtest: clean up dependencies of boot-smoke test

A lot of the dependencies are not needed but were originally added to
avoid a testbed reset and make it possible to reuse the testbed of the
upstream test. This turned out to be a maintenance problem and the
dependencies were not updated accordingly. Instead of trying to keep the
two tests in sync, trim down the boot-smoke dependencies to its bare
minimum.