Drop test code for narrow builds of Python

[SnoopJ]

There is some code in the unicodedata2 test associated with narrow (UCS2-only) builds of Python. I believe this code was added (in #35) when unicodedata2 was still supporting Python 2 and versions before Python 3.3 when narrow builds were removed.

As far as I know, this code is entirely dead now that unicodedata2 does not support these older versions of Python.

(context: I noticed this while diffing the test suite against the upstream tests as I organize a PR for #60)