Review removed threads

[jbudynk]

In the old testdata directory, we found that many of the threads/ directories aren't tested by the sherpa regression tests. We removed these before creating sherpa-test-data. We should

• figure out why they aren't tested
• create regression tests for these threads if necessary, and
• see if there's an external regression test suite that uses these threads

For a list of the removed threads and files, see section "Files" under 4.8->features->new-test-infrastructure->testdata on the Sherpa Dokuwiki.