This sets the end date for the Xena key, adds the Yoga key starting
today and links to an export of the corresponding public key. It
also drops references to the now defunct SKS keyserver network and
our old rotation process which was tied to it. Instead the key has
been created following the new process described by change
I7008706aae06b6e4a16db2dd85a8c7f91530cd50.
Depends-On: https://review.opendev.org/815548
Change-Id: I53f11a249b5e09c84d65644ee609553a9b6e6353
17a9198869