gitlab-operator-build-base image: Update to Go v1.18.6 and v1.19.1

Context

The following discussion from !582 (merged) should be addressed:

@stanhu started a discussion:

I didn't want to touch gitlab-operator since upgrading to 1.19 would also mean updating to Alpine 3.16, but I don't have enough context about https://gitlab.com/gitlab-org/gitlab-build-images/-/blob/7d5f25b97ef6ad33b7e528d8d948374ebf896532/Dockerfile.gitlab-operator-build-base#L3-5. Maybe @mnielsen you know?

Edited Sep 27, 2022 by Mitchell Nielsen