Define thirdparty-requirements.txt for functest-parser

Define thirdparty-requirements.txt for functest-parser

As Parser python packages has been renamed, they can be defined in
upper-constraints.txt. No conflict can occur between them and the
official OpenStack packages.

The Parser testcase still requires a dedicated container to avoid
conflicts in namespaces.

Conflicts:
    docker/parser/Dockerfile
    upper-constraints.txt

Change-Id: Ic8d18140f26e72d1e3d04b73d301d3fd870b171a
Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>
(cherry picked from commit f77c464a9bf40b36586843ae59e6764216477c4b)