fix!: use generic variables when registry is shared

[jackhodgkiss]

No description provided.

[markgoddard]

I thought we agreed to always use specific variables and secrets when using multiple environments to make the docs simpler.

[jackhodgkiss]

I thought we agreed to always use specific variables and secrets when using multiple environments to make the docs simpler.

I did have a good reason for wanting to make this change but I can't remember. Let me compare output and I will update the commit with motivation as to why I made this change half a year ago.

[markgoddard]

I thought we agreed to always use specific variables and secrets when using multiple environments to make the docs simpler.

I did have a good reason for wanting to make this change but I can't remember. Let me compare output and I will update the commit with motivation as to why I made this change half a year ago.

A lesson in the benefit of detailed commit messages. For others and future you.