ci: on release branch builds, never cache client bundle
Created by: jhchabran
Follow up to @eseliger's great suggestion here https://github.com/sourcegraph/sourcegraph/pull/39031#pullrequestreview-1043381407
Test plan
Tested locally.
Created by: jhchabran
Follow up to @eseliger's great suggestion here https://github.com/sourcegraph/sourcegraph/pull/39031#pullrequestreview-1043381407
Tested locally.