Allow setting postUpdateOptions in an environment variable

[BrianHicks]

Tell us more.

I expected to be able to set RENOVATE_POST_UPDATE_OPTIONS to set the default for my installation. However, this environment variable doesn't appear to be read! Instead, I ended up setting RENOVATE_CONFIG with some JSON that included postUpdateOptions. This works, but was an unexpected piece of friction. It'd be nice if I could just set the environment variable for the default directly.

[jamietanna]

Can you share more about your use-case? We're trying to reduce what makes sense under environment variables (#42161)

Given this is something that can be set in Repo, shared or Global Self-Hosted config, is there any reason it's something you'd want to set in the environment?

[BrianHicks]

I've moved on from the circumstance that needed this and I don't remember exactly what it was. Maybe something to do with go mod?

But basically: yes, it could be set in config! But all the other config options in this project were set in environment variables, yet this one couldn't be. It was surprising and took a little bit of work to track down since there was parity between the two sources everywhere else.