test-terminate-replay: reduce GC sensitivity

I saw a test failure here, "historical inaccuracy in replay", which
might have been due to GC happening one way in the original, and a
different way in the replay (when running under Node.js). This feels
like an aspect of #5575, and this test isn't trying to exercise
anything about GC, so I'm just going to set defaultReapInterval to
'never' to inhibit BOYD, which should remove the problem.

packages/SwingSet/test/vat-admin/terminate/test-terminate-replay.js

@@ -19,6 +19,7 @@ test.serial('replay does not resurrect dead vat', async t => {
   const configPath = new URL('swingset-no-zombies.json', import.meta.url)
     .pathname;
   const config = await loadSwingsetConfigFile(configPath);
+  config.defaultReapInterval = 'never';
 
   const ss1 = initSwingStore();
   {