install_arch: preserve stock nsswitch.conf

Leaving "dns" out of "hosts" breaks DNS lookups when resolved is
stopped.

roles/install_arch/tasks/main.yml

@@ -149,12 +149,6 @@
 - name: configure grub
   command: chroot /mnt grub-mkconfig -o /boot/grub/grub.cfg
 
-- name: configure nss
-  lineinfile:
-    dest: /mnt/etc/nsswitch.conf
-    regexp: '^hosts:'
-    line: 'hosts: files mymachines resolve myhostname'
-
 - name: enable services inside chroot
   command: chroot /mnt systemctl enable sshd systemd-networkd systemd-resolved fstrim