tox: Move the whitelist_externals to testenv section

1. move the whitelist_externals to testenv

Change-Id: I12bd4f8a9b633cfb252fccebcee8214d309c1a56

tox.ini

@@ -5,8 +5,13 @@ envlist = py37,pep8,mypy,py27
 
 [testenv]
 usedevelop=True
-whitelist_externals = find
-                      bash
+whitelist_externals =
+  find
+  bash
+  make
+  mkdir
+  mypy
+  rm
 install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master} {opts} {packages}
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
@@ -70,7 +75,6 @@ commands =
 [testenv:mypy]
 basepython = python3
 skip_install = true
-whitelist_externals = mypy
 commands =
   mypy --py2 --ignore-missing-imports kolla_cli
 
@@ -89,7 +93,6 @@ commands = bandit -r kolla_cli -x tests
 
 [testenv:docs]
 basepython = python3
-whitelist_externals = rm
 deps =
    {[testenv]deps}
    -r{toxinidir}/doc/requirements.txt
@@ -99,10 +102,6 @@ commands =
 
 [testenv:pdf-docs]
 basepython = python3
-whitelist_externals =
-  make
-  mkdir
-  rm
 deps = {[testenv:docs]deps}
 commands =
     rm -rf doc/build/pdf
@@ -112,7 +111,6 @@ commands =
 
 [testenv:releasenotes]
 basepython = python3
-whitelist_externals = rm
 deps =
    {[testenv]deps}
    -r{toxinidir}/doc/requirements.txt