\Drupal\Tests\update\Functional\UpdateTestBase::setUp is not needed for most child classes and makes the test harder to understand

Problem/Motivation

\Drupal\Tests\update\Functional\UpdateTestBase::setUp()

Is only needed for FileTransferAuthorizeFormTest and UpdateUploadTest

All other test classes that extend UpdateTestBase would pass without these. But if you were trying work on these tests this would be very hard for you to understand. I am the maintainer of the Update I even had to just remove this method and see what broke.

Leaving this method where it is bad because:

1. It risks us making accidently a change that means other classes will only pass with method running
2. It makes that tests take longer because it make directory for every test case, and there are a lot
3. It makes understanding the tests harder because you can't rule that this method is affecting the test you are trying to understand

Proposed resolution

Remaining tasks