Simplify testsuite driver

Summary:
- remove clean_cmd
- framework_failures was undefined
- times_file was not used
- if_verbose_dump was called only when verbose >= 1; remove the check
- simplify normalise_whitespace

Test Plan: validate

Reviewers: bgamari, thomie

Reviewed By: thomie

Subscribers: rwbarton, carter

Differential Revision: https://phabricator.haskell.org/D5061