fix: ensure we wait for the inspect to disconnect

This re-orders our node clean up so that we free the environment before
the task runner is cleaned up as node uses the task runner during clean
up.  It also calls WaitForDisconnect() to ensure that inspector agents
are notified that the context is going down.

spec/node-spec.js

@@ -390,6 +390,7 @@ describe('node feature', () => {
             const connection = new WebSocket(socketMatch[0])
             connection.onopen = () => {
               child.send('plz-quit')
+              connection.close()
               done()
             }
           }