Define default OS_TEST_TIMEOUT for every tempest tox env

Currently only 'all' tox env define the default OS_TEST_TIMEOUT
which is 1200. Any other tox env which run tempest test does not
have any default value for test timeout.

We should define default OS_TEST_TIMEOUT in every such env like
'all'.

Change-Id: I0dc4c940bbb22321b42e0f242aea5c1b5f45a5ae
diff --git a/tox.ini b/tox.ini
index 64921ef..a8a2297 100644
--- a/tox.ini
+++ b/tox.ini
@@ -10,6 +10,7 @@
 setenv =
     VIRTUAL_ENV={envdir}
     OS_TEST_PATH=./tempest/test_discover
+    OS_TEST_TIMEOUT={env:OS_TEST_TIMEOUT:1200}
 deps =
     -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
     -r{toxinidir}/requirements.txt
@@ -61,7 +62,6 @@
 # 'all' includes slow tests
 setenv =
     {[tempestenv]setenv}
-    OS_TEST_TIMEOUT={env:OS_TEST_TIMEOUT:1200}
 deps = {[tempestenv]deps}
 commands =
     find . -type f -name "*.pyc" -delete
@@ -79,7 +79,6 @@
 # 'all' includes slow tests
 setenv =
     {[tempestenv]setenv}
-    OS_TEST_TIMEOUT={env:OS_TEST_TIMEOUT:1200}
 basepython = {[tempestenv]basepython}
 deps = {[tempestenv]deps}
 commands =
@@ -93,7 +92,6 @@
 # 'all' includes slow tests
 setenv =
     {[tempestenv]setenv}
-    OS_TEST_TIMEOUT={env:OS_TEST_TIMEOUT:1200}
 basepython = {[tempestenv]basepython}
 deps = {[tempestenv]deps}
 commands =