dev/ci: unify traps to ensure cluster cleanup
Created by: bobheadxi
Looks like https://github.com/sourcegraph/sourcegraph/pull/24600 caused the cluster cleanup to get overridden, I think this will fix it?
https://buildkite.com/sourcegraph/sourcegraph/builds/107622
https://buildkite.com/sourcegraph/qa/builds/5397#ea628b8b-8a4e-4704-8a96-b1aa61a34259/77-1127