Enable Doctor testcase

Enable Doctor testcase

It upates upper-constraints.txt and thirdparty-requirements.txt as
doctor-test was renamed to doctor-tests.

It installs the doctor packages and its requirements via python3.
Then python_version>='3.0' conditions are added to avoid installing
them for python2.

It also calls the new console scripts and modifies the installer
list supporting it.

Conflicts:
    upper-constraints.txt

Co-Authored-By: Cédric Ollivier <cedric.ollivier@orange.com>
Change-Id: Icd855f4534d9d9591165e99aa0eed6b1030018e0
Signed-off-by: dongwenjuan <dong.wenjuan@zte.com.cn>
Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>
(cherry picked from commit 1e1fba3aa18ebcbff6746586654805a44e88e9fe)