Update to Go 1.18.7

What does this MR do?

Go 1.17.x is no longer receiving updates. Security announcement for 1.18: https://groups.google.com/g/golang-announce/c/xtuG5faxtaU

Related issues

Part of gitlab-org&8843 (closed)

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion

Required

• Merge Request Title, and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Integration tests added to GitLab QA
• The impact any change in container size has should be evaluated