[plugin] fix: dispose deploy listener on close

[ensorrow]

What it does

The deploy listener won't dispose when connection got disposed, which will cause memory leak.

How to test

1. Lower the max listener count in theia/packages/core/src/common/event.ts
2. trying to disconnect the client (you can use the proxy below to simulate the disposed connection)

var express = require('express');
var app = express();
var httpProxy = require('http-proxy');
var proxy = httpProxy.createProxyServer({ target: 'http://localhost:3000', ws: true });

var server = require('http').createServer(app);

// proxy HTTP GET / POST
app.get('/*', function (req, res) {
  console.log("proxying GET request", req.url);
  proxy.web(req, res, {});
});
app.post('/*/*', function (req, res) {
  console.log("proxying POST request", req.url);
  proxy.web(req, res, {});
});

// Proxy websockets
server.on('upgrade', function (req, socket, head) {
  console.log("proxying upgrade request", req.url);
  proxy.ws(req, socket, head);
});

server.listen(3001);

Review checklist

• as an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• as a reviewer, I agree to behave in accordance with the review guidelines

[akosyakov]

@ensorrow please sign your work and accept ECA, otherwise we cannot continue

[ensorrow]

@ensorrow please sign your work and accept ECA, otherwise we cannot continue

Done

[akosyakov]

@ensorrow thank you @marcdumais-work i am not sure why eca check is still not happy

Maybe an empty line is required before sign-off line.

[akosyakov]

Changes looks good and make sense to me.

[benoitf]

@ensorrow

the Signed-Off and the commit e-mail should be the same

Author: xunhe.lzy <.....@alibaba-inc.com>

Signed-off-by: Louis Lv <.....@qq.com>

[akosyakov]

eca is still not happy :( cc @marcdumais-work

[ensorrow]

Too busy to fix eca problem in time, sorry for that @akosyakov

[akosyakov]

@ensorrow thank you for dealing with ECA check :)