Use pkg_interpreter_for and remove core/coreutils
Use pkg_interpreter_for and remove core/coreutils

We should use proper habitat helper methods to get this information like
a package interpreter: https://www.habitat.sh/docs/reference/#plan-helper-functions

Signed-off-by: Salim Afiune <2b0aff3923bd0ab6bbf45ffb37e57dcea8e1b0b8@chef.io>

chef/chef-dk,chef/chef-dk,chef/chef-dk