running chown and chmod on files and folders not created by
devstack causes a few issues:
* On nfs mounted directories it can take an extremely
long time to chown -R some of the git repos, especially
if any tox commands have been ran in the host
* chown can cause the host files to get into a weird state
if nfs is set up wrong.
If files and folders are pre-existing we should assume
they are in the correct state, and not modify them.
Fix setup-devstack-log-dir to create the logs directory with
correct permissions in the first place.
Change-Id: I5ebdaded3ffd0a5bc70c5e9ab5b18daefb358f58
Signed-off-by: Graham Hayes <gr@ham.ie>
352d58a7af