Fix up file-matching in bashate tox test

The current test does not match file files in /lib/* because the
-wholename command is missing the preceeding \*.  The whole command is
a little difficult to understand.

This re-lays the find command, using -prune to skip dot directories
and keeping a hopefully clearer flow of what is being matched.

Change-Id: Idd856e897ff97095fb116294a9187ff4b198fa26
Merge "Fix up file-matching in bashate tox test"