This update offers two changes:

* More intelligent error reporting for non UTF-8 TAP13 output ([1],
  [2]).
* Restart tarantool server before each test (to avoid unexpected and
  non-obvious dependencies between tests, see [3]).

Removed the pretest_clean suite.ini option: test-run does not read it
anymore.

[1]: https://github.com/tarantool/test-run/issues/293
[2]: https://github.com/tarantool/test-run/pull/297
[3]: https://github.com/tarantool/test-run/pull/309