fix(yarn): bump k8s memory limit for yarn:pack jobs

As noted in #158 (closed), the default memory limit for yarn:pack jobs is a little tight. In uis/devops/tools/gitlab-utils!214 (merged) it was noted that 1.5Gi suffices for a relatively simple TypeScript -> static site application and so set the limit conservatively to 2Gi expecting other uses to be a little more complex.

It's likely we'll need to bump this over time but this is at least a limit observed to suffice for one user.

Tested with the smaller 1.5Gi limit in uis/devops/tools/gitlab-utils!214 (merged)

Closes #158 (closed)