remove tools/jenkins

The last non bashate change in this directory was from 2012, which
means I assume nothing down here is useful any more as this is largely
the precursor to devstack-gate.

Remove it for cleanliness reasons and to not confuse people setting
up 3rd party ci.

Change-Id: I54f06c2ff5a49a9f811df07a7cdfda4a675953c8

Author: sdague