Sort out how to deal with GKE updates as we turned them off for the buildkite cluster

Created by: jhchabran

Context:

• https://github.com/sourcegraph/devx-scratch/blob/main/2022/support/log.snb.md?rgh-link-date=2022-07-06T11%3A58%3A19Z#2022-07-05
• https://sourcegraph.slack.com/archives/C01N83PS4TU/p1657100536366069
• https://github.com/sourcegraph/infrastructure/pull/3624

As those are now manual, we'll need to upgrade those on our own time.

Openers to dig into this:

• What happens if we don't do this? Is that going to be a sec problem?
• Can a gcal event be good enough?
• How do we avoid interrupting CI operations?

@quinnhare I've assigned you as a way to put it on your radar!