build_chroot: use APT_INSTALL macro for packet installation
build_chroot: use APT_INSTALL macro for packet installation

In this way, it is easier to change all the apt calls in the chroot.
In particular, this patch fixes the missing -y option for the installation
of the tools needed to build debian packages.

Signed-off-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>
Reviewed-by: Michele Tartara <05f7077a2c6cbbdc4af4ba42e3ef89a0df846179@google.com>

mbakke/ganeti,mbakke/ganeti,ganeti-github-testing/ganeti-test-1,yiannist/ganeti,yiannist/ganeti,bitemyapp/ganeti,apyrgio/ganeti,andir/ganeti,onponomarev/ganeti,apyrgio/snf-ganeti,bitemyapp/ganeti,mbakke/ganeti,grnet/snf-ganeti,ganeti/ganeti,andir/ganeti,ganeti/ganeti,dimara/ganeti,leshchevds/ganeti,apyrgio/ganeti,ganeti/ganeti,grnet/snf-ganeti,leshchevds/ganeti,yiannist/ganeti,leshchevds/ganeti,andir/ganeti,apyrgio/snf-ganeti,onponomarev/ganeti,ganeti-github-testing/ganeti-test-1,dimara/ganeti