testsuite: remove EggTestSuite

We no longer run tests with `python setup.py`, but simply with `python -m unittest`
2 jobs for <span class="ref-name">fix/no-EggTestSuite</span> in 0 seconds
Status Job ID Name Coverage
  External
passed SlapOS.Eggs.UnitTest-Jerome.Python2

00:21:02

passed SlapOS.Eggs.UnitTest-Jerome.Python3

00:10:29