Use upper-constraints.txt file for all tox targets

The only targets that are left unconstrained are those that belong to
post merge queues where constraints are not yet available.

Change-Id: I0546be87a0bb2a34b8c030d883ede3c45e6d6f54

tox.ini

@@ -6,7 +6,8 @@ skipsdist = True
 [testenv]
 usedevelop = True
 setenv = VIRTUAL_ENV={envdir}
-install_command = pip install -U {opts} {packages}
+install_command =
+    pip install -U -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}
 whitelist_externals = find
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
@@ -16,6 +17,8 @@ commands =
   python setup.py testr --slowest --testr-args='{posargs}'
 
 [testenv:cover]
+# TODO(ihrachys): remove once infra supports constraints for this target
+install_command = pip install -U {opts} {packages}
 commands = python setup.py testr --coverage --testr-args='{posargs}'
 
 [testenv:debug]
@@ -38,6 +41,8 @@ commands = flake8
 commands = python setup.py build_sphinx
 
 [testenv:venv]
+# TODO(ihrachys): remove once infra supports constraints for this target
+install_command = pip install -U {opts} {packages}
 commands = {posargs}
 
 [testenv:genconfig]
@@ -74,4 +79,6 @@ local-check-factory = octavia.hacking.checks.factory
 max-line-length = 79
 
 [testenv:releasenotes]
+# TODO(ihrachys): remove once infra supports constraints for this target
+install_command = pip install -U {opts} {packages}
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html