microvm-defaults: also increase conntrack table for 2G RAM

modules/microvm-defaults.nix

@@ -13,7 +13,7 @@
       let
         mem = if (config?microvm) then config.microvm.mem else config.deployment.mem;
       in
-      lib.optionalAttrs (mem <= 1024) {
+      lib.optionalAttrs (mem <= 2*1024) {
         # table overflow causing packets from nginx to the service to drop
         # nf_conntrack: nf_conntrack: table full, dropping packet
         "net.netfilter.nf_conntrack_max" = "65536";