Remove double addition of test suite

Remove double addition of test suite

The original purpose of adding the default timeout tests twice
does not seem to be relevant anymore; the timeout tests have been
split into several different types, each using either the
tcase_set_timeout or an environment variable. The tc_timeout_default
suite never has anything but the default timeout set, so the
spirit of why it was originally added no longer applies.
In addition, if the suite were formally torn down it would cause
a double free error.