Bump Golang version in Gitaly UBI image
What does this MR do and why?
Update the Golang version in Gitaly UBI image to Go 1.18.
The original MR which added it (!559 (merged)) kinda raced against the upstream change in gitaly!4684 (merged) where the default version was changed to Go 1.18. These missing images caused errors in https://gitlab.com/gitlab-org/gitaly/-/pipelines/581659230 https://gitlab.com/gitlab-org/gitaly/-/pipelines/581690262 https://gitlab.com/gitlab-org/gitaly/-/pipelines/581691792
Edited by Balasankar 'Balu' C