Delete Generator/discriminant test

[karkhaz]

This test is flaky in CI; removing until we can diagnose and fix the failure.

Description of changes:

Describe Kani's current behavior and how your code changes that behavior. If there are no issues this PR is resolving, explain why this change is necessary.

Checklist

• Each commit message has a non-empty body, explaining why the change was made
• Methods or procedures are documented
• Regression or unit tests are included, or existing tests cover the modified code
• My PR is restricted to a single feature or bugfix

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 and MIT licenses.

[qinheping]

Can we instead make it a fixme test and create an issue to remind us to fix it later? https://model-checking.github.io/kani/regression-testing.html#fixme-tests

Haven't read the slack message before approval

[karkhaz]

I'm not sure if fixme would work here because the test is flaky. It sometimes appears to memout in CI, but otherwise works. So we can't add an expected result I think...

[zhassan-aws]

I agree adding fixme won't work because the test sometimes passes, so the kani-fixme suite may fail.

But, as @qinheping pointed out, can we at least file an issue to track re-enabling this test?

[karkhaz]

Yes, opened #2337