nixosTests.postgresql: run tests with JIT as well

This was intended for quite some time already, but ever since enableJIT
was changed to be the source of truth of JIT-iness for the PostgreSQL
module, this hasn't worked for the tests anymore.

nixos/tests/postgresql/postgresql-tls-client-cert.nix

@@ -50,6 +50,7 @@ let
           services.postgresql = {
             inherit package;
             enable = true;
+            enableJIT = lib.hasInfix "-jit-" package.name;
             enableTCPIP = true;
             ensureUsers = [
               {