Fix open handle in tests

[jeddy3]

I got this while running our tests:

Running coverage on untested files...A worker process has failed to exit gracefully and has been force exited. 
This is likely caused by tests leaking due to improper teardown. Try running with --runInBand --detectOpenHandles to find leaks.

And the following:

npm run jest -- --runInBand --detectOpenHandles

Returns:

Jest has detected the following 1 open handle potentially keeping Jest from exiting:

  ●  TTYWRAP

      14 | 
      15 |      beforeAll(() => {
    > 16 |              processRestore = { ...process };
         |              ^
      17 |              logRestore = { ...console };
      18 |              process.exit = (exitCode) => (process.exitCode = exitCode);
      19 |      });

      at Object.<anonymous> (system-tests/cli/cli.test.js:16:3)

[exoer]

I got this while running our tests:

Running coverage on untested files...A worker process has failed to exit gracefully and has been force exited. 
This is likely caused by tests leaking due to improper teardown. Try running with --runInBand --detectOpenHandles to find leaks.

And the following:

npm run jest -- --runInBand --detectOpenHandles

Returns:

Jest has detected the following 1 open handle potentially keeping Jest from exiting:

  ●  TTYWRAP

      14 | 
      15 |      beforeAll(() => {
    > 16 |              processRestore = { ...process };
         |              ^
      17 |              logRestore = { ...console };
      18 |              process.exit = (exitCode) => (process.exitCode = exitCode);
      19 |      });

      at Object.<anonymous> (system-tests/cli/cli.test.js:16:3)

@jeddy3 You might want to try something like this

afterAll(()=>{
   processRestore = null
    ...
})

[jeddy3]

@exoer Thanks for the suggestion. @hudochenkov refactored these tests in #4601 and I believe the issue was resolved.