gitlab-ci: rename amd64 to x86_64 to distinguish from arm64
I keep confusing amd64 with arm64 when reading the two, so I'd like
to rename one to something that looks different.
Due to an influx of spam, we have had to impose restrictions on new accounts. Please see this wiki page for instructions on how to get full permissions. Sorry for the inconvenience.
The migration is almost done, at least the rest should happen in the background. There are still a few technical difference between the old cluster and the new ones, and they are summarized in this issue. Please pay attention to the TL:DR at the end of the comment.
I keep confusing amd64 with arm64 when reading the two, so I'd like
to rename one to something that looks different.