Fix cleanup of check-osc-plugins
Fix cleanup of check-osc-plugins

Fix pasto, the directory to clean is venv_name. Also, add trap first in
case the virtualenv command fails.

Change-Id: Iad5c38b816c6c231b14da3f9b4d423c9aa230189

openstack-infra/project-config,Tesora/tesora-project-config,openstack-infra/project-config,noorul/os-project-config,noorul/os-project-config,dongwenjuan/project-config,dongwenjuan/project-config,Tesora/tesora-project-config