Scale back on tripleo testing

Remove the check-tripleo-seed-precise job jobs as its currently a subset
of the undercloud and overcloud jobs.

Move the check-tripleo-ironic-undercloud-precise into the
tripleo-experimental queue, it currently doesn't pass, once its fixed we
can replace the ironic seed job with it.

Change-Id: I1113f8117bd201255386b9d8daa9b6bada018bbb
Merge "Scale back on tripleo testing"