unbound(role): reformat config template and use all vcpus

roles/unbound/templates/unbound.conf.j2

@@ -2,17 +2,13 @@
 #      unbound.conf(5) man page
 server:
   {% if unbound_enable_dnssec -%}
-    # disable chroot because unbound is the only thing running on the VM
-    # and because it has issues with how archlinux configures the systemd units write protection regarding the anchor file
-    chroot: ""
-
   # location of the trust anchor file that enables DNSSEC
   # this file is generated by the `unbound-anchor` command
   auto-trust-anchor-file: "/etc/unbound/trusted-key.key"
   {% endif -%}
 
 	# use all CPUs
-	num-threads: 2
+	num-threads: {{ ansible_facts['processor_vcpus'] }}
 
 	# more cache memory
   rrset-cache-size: 60m
@@ -69,5 +65,4 @@ auth-zone:
   for-downstream: no
   for-upstream: yes
 
-
 {% endfor %}