vm_setup: Preserve environment when calling sudo

Make sure that environment is preserved for each call to sudo to, e.g.
make sure proxy configuration is not lost when executing given package
manager.

Change-Id: If221d8d6546fc0ae4f02bc5814b6688c6d78cdd6
Signed-off-by: Michal Berger <michalx.berger@intel.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/2739


Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Community-CI: Mellanox Build Bot
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Paul Luse <paul.e.luse@intel.com>
Reviewed-by: Karol Latecki <karol.latecki@intel.com>