Problem/Motivation
We are converting all our test cases to use PHPUnit which is a well known and well supported test runner. Maintaining the Simpletest UI is a lot of work, we should rather spend our resources on good developer docs for running our PHPUnit tests from the command line and from IDEs.
Note: You can get the same output as with the simpletest UI using --browser --verbose. This issue is about mostly the listing page of all available tests.
Proposed resolution
Remove Simpletest's UI as soon as 90% of our test cases are converted to PHPUnit tests, see also #2735005: Convert all Simpletest web tests to BrowserTestBase (or UnitTestBase/KernelTestBase).
Remaining tasks
Discuss the consequences of removing Simpletest UI and build agreement.
User interface changes
No more running test cases from Drupal's UI.
API changes
Since this change only affects test code and not end user facing features it is exempt from the API and UI change policies.
Data model changes
none.