Use pylint to identify style and convention errors in
xscriptprovider.py. Also make use of setUp and tearDown
methods to streamline the class and reduce code
duplication.

Change-Id: Iee4addb6577c304c5ced4e2d246c4bb557d2b6f4
Reviewed-on: https://gerrit.libreoffice.org/66197
Tested-by: Jenkins
Reviewed-by: Samuel Mehrbrodt <Samuel.Mehrbrodt@cib.de>