nixos/postgresql: fix enableJIT = false

The enableJIT = true case was fixed in #221851 or
e2fb65175228a992f196f3b1700a53e18602e7f6 respectively.

However this did not take the case into consideration, when doing this:

services.postgresql = {
enable = true;
enableJIT = false;
package = pkgs.postgresql_15_jit;
};

If enableJIT is treated as the source of truth, then this should indeed
cause JIT to be disabled, which this commit does.

Changed files
+1 -1
nixos
modules
services
databases
+1 -1
nixos/modules/services/databases/postgresql.nix
···
# package = pkgs.postgresql_<major>;
# };
# works.
-
base = if cfg.enableJIT then cfg.package.withJIT else cfg.package;
+
base = if cfg.enableJIT then cfg.package.withJIT else cfg.package.withoutJIT;
in
if cfg.extraPlugins == []
then base