fix(tvl-sso): set memory limit to 512M

This is because I'm bored of CAS gradually consuming all the RAM on Whitby.

Change-Id: Idcc14c19d99a6d3553739c5765be3faf2bdf9d84
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3233
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>
Reviewed-by: tazjin <mail@tazj.in>

ops/modules/tvl-sso/default.nix

@@ -10,6 +10,7 @@ in {
       description = "Apereo CAS Single Sign On server";
       wantedBy = [ "multi-user.target" ];
       after = [ "network.target" ];
+      environment.JDK_JAVA_OPTIONS = "-Xmx512M -Xms512M";
       serviceConfig = {
         User = "apereo-cas";
         Group = "apereo-cas";