tests/helper-runtests.sh

packaging: remove hg-ssh.8.html from Inno installer

We don't ship hg-ssh because it requires a python.exe to
run, which we don't ship. So it doesn't make sense to ship
the HTML documentation for this tool.

This change makes the Inno install layout more consistent
with WiX, which doesn't ship this file.

Functionality for removing files has been made generic,
in anticipation of future expansion.

Differential Revision: https://phab.mercurial-scm.org/D7169

#
# Avoid interference from actual test env:

unset HGTEST_JOBS
unset HGTEST_TIMEOUT
unset HGTEST_PORT
unset HGTEST_SHELL