Bug: using a "dynamic" restart=false with webdriverio backend leaves browser instances running

#### What are you trying to achieve?

I'm trying to configure a single feature to keep the browser open between tests.
Configuring globally is not an option because our tests are not ready to handle that yet.
I want to have some tests run with browser restart: true, and others with restart: false.

I'm running the following command:
```bash
codeceptjs run path-to-my-test
```

I expect the browser to close after tests are executed.

(All tests pass btw.)

#### What do you get instead?

Browser remains open after all tests finish.

```bash
› [Suite Config] WebDriver {"restart":false}
› Started SeleniumStandaloneLauncher
› [Session] Starting singleton browser session
› [Window Size] [object Object]

# ...
# irrelevant tests output
# ....

Emitted | test.after ([object Object])
› [Session] cleaning cookies and localStorage
Emitted | suite.after ([object Object])
› [Suite Config] Reverted for WebDriver

OK | 7 passed // 23s
Emitted | global.result ([object Object])
Emitted | global.after ([object Object])
› Stopped SeleniumStandaloneLauncher
```

> Provide test source code if related

```js
Feature('Feature').config('WebDriver', {
restart: false,
});
```

### Details

* CodeceptJS version: ^2.3.2
* NodeJS Version: v10.15.3
* Operating System: Ubuntu 19.04
* Protractor || WebDriverIO || Nightmare version (if related): ` "@wdio/selenium-standalone-service": "^5.15.0",`
* Configuration file:

```js
helpers: {
GraphQL: {
endpoint: 'http://localhost:4060/graphql',
},
WebDriver: {
url: 'http://localhost:4050/',
browser: 'chrome',
windowSize: 'maximize',
version: chromeVersion,
desiredCapabilities: {
chromeOptions: {
binary: process.env.CI ? void 0 : chromiumBinary.path,
args: ['--disable-gpu'],
},
},
smartWait: 5000,
},
},
```

Related but not the same: https://github.com/Codeception/CodeceptJS/issues/1069