unbound: fix log rotation

Was too frequent, now that we only log SERVFAILs.
Rotate according to file size.
Fix unbound-control binary path.

roles/unbound/templates/unbound-logrotate.j2

@@ -1,6 +1,6 @@
 /var/log/unbound/*.log {
-	daily
-	rotate 30
+	size 1G
+	rotate 4
 	missingok
 	notifempty
 	compress
@@ -8,6 +8,6 @@
 	sharedscripts
 	create 644
 	postrotate
-		/usr/local/sbin/unbound-control log_reopen
+		/usr/sbin/unbound-control log_reopen
 	endscript
 }