Drop lock_path section from config guide

This commit drops the lock_path section from the tempest config guide.
Previously setting this was required there was no default value from
the oslo lib. However, tempest recently switched to overriding the
default to use the system temp dir. So additional configuration by the
end user should not be required here anymore.

Change-Id: Ia594745ad4d8e6b701c799cbf5ac5e555c598e3f
1 file changed