See HIVE-2034 where we bumped to 1.19.

IIUC what we need to do here is in multiple steps, and I think the order is important:
1. A PR similar to https://github.com/openshift/release/pull/33821 to make CI build against the new image.
2. A PR similar to https://github.com/openshift/hive/pull/1910 which just bumps the FROM in build/build-image/Dockerfile.
3. Wait for... something?
4. A PR similar to https://github.com/openshift/hive/pull/1907 to finish changing all the references.

Assignee, please keep track of the actual steps and open a new card for 1.21.