Changes

testenv: install dbg pkgs with --binary-repo too

When using --binary-repo, figure out the -dbg and -dbgsym packages for
all dependencies of packages to be installed, and install them as well.

This will make debug symbols available in jenkins, useful for the
related issue. Before this patch debug symbols were only available when
building locally without --binary-repo.

Related: OS#6630
Change-Id: I4dc57257b944126fed2c7b031c92c77a3d4286e0