This sets the end date for the Stein key, adds the Train key
starting today and links to a minimal export of the corresponding
public key and its details on the keyserver network. The key
material change (Depends-On below) merged and went into effect
2019-06-11.
Change-Id: I843d7025341e4226cbdb70572d1960096fdd0bfc
Depends-On: https://review.opendev.org/664675