Refactor: python: Improve reattach.py.

• Disable pylint warnings we can't really do anything about.

• Use %r instead of repr in format strings.

• Rename stopall to _stopall since it is a private attribute.

• Remove the unused restart1 attribute.

• Use the correct return values in setup and teardown. This will ensure errors in these functions count towards the success/failure stats.

• Get rid of is_unsafe and is_applicable. These don't do anything different from the superclass versions.