Removing unused directory "etc/oslo-config-generator" from kolla-ansible

"etc/oslo-config-generator" is being use in kolla repo
too.
Closes-Bug: #1652650

Change-Id: I012830ac3212ebfe954483f076f84541f609bb44

etc/oslo-config-generator/kolla-build.conf

-[DEFAULT]
-output_file = etc/kolla/kolla-build.conf
-namespace = kolla

tox.ini

@@ -44,11 +44,6 @@ commands =
   {toxinidir}/tools/setup_gate.sh
   {toxinidir}/tools/dump_info.sh
 
-[testenv:genconfig]
-whitelist_externals = which
-commands=
-  oslo-config-generator --config-file etc/oslo-config-generator/kolla-build.conf
-
 [testenv:releasenotes]
 commands =
   rm -rf releasenotes/build