Drop Train designate scenario job

Designate marked Train as EOL with [1] and stable/train
branch removed for it. This patch removes the job as
it's now failing.

[1] https://review.opendev.org/c/openstack/releases/+/862956

Change-Id: I44fd3b21bee3eeb4bfd2e8ed06c73b372ada77a4
2 files changed