Fix jest tests

[marthacryan]

Fixes the jest test failures by updating the testutils version. Changes to using port 8890 by default for tests to avoid conflicts when JupyterLab is running.

Edit: no longer changes the port used by tests because of #1024

Developer's Certificate of Origin 1.1

   By making a contribution to this project, I certify that: 799189
   (a) The contribution was created in whole or in part by me and I
       have the right to submit it under the Apache License 2.0; or

   (b) The contribution is based upon previous work that, to the best
       of my knowledge, is covered under an appropriate open source
       license and I have the right under that license to submit that
       work with modifications, whether created in whole or in part
       by me, under the same open source license (unless I am
       permitted to submit under a different license), as indicated
       in the file; or

   (c) The contribution was provided directly to me by some other
       person who certified (a), (b) or (c) and I have not modified
       it.

   (d) I understand and agree that this project and the contribution
       are public and that a record of the contribution (including all
       personal information I submit with it, including my sign-off) is
       maintained indefinitely and may be redistributed consistent with
       this project or the open source license(s) involved.

[elyra-bot]

Thanks for making a pull request to Elyra!

To try out this branch on binder, follow this link:

[lresende]

Could we update this on master (on top of #1024).

[marthacryan]

@lresende Just tested locally on master and the newer version of testutils doesn't work with JupyterLab 2.2.9 due to server changes in 3.0, so I think we should keep this as a PR to the jupyterlab3 branch

[marthacryan]

Also note: just removed the changes from the last two commits because they were duplicates of #1024 - this PR now only changes the version of the JupyterLab testutils.