Clients.py: add back the default_params_with_timeout_values class variable

Id518a6d87d0949737cd1c50cb6a83149b85e5f85 removes this class variable
because we thought no one was using it anymore. We were wrong and broke
some Tempest plugins. But this variable shouldn"t have been used in the
first place because it's a private/internal variable only. So we
expect plugins will eventually remove their dependency on that var.

Change-Id: Iac926f12cf3a1681a596f0ba7d014a402cda5fa0
1 file changed