PR comment should take in account allowed stages

[mchv]

When the riff-raff config does not contains CODE as a staging environment it seems odd to default to it. Similarly when allowedStage contain only one stage (PROD or INFRA for instance), my expectation will be top use it rather than defaulting to CODE.

[akash1810]

Not sure how this would play with the commentingStage property 🤔.

[akash1810]

Wonder what the behaviour should be if allowedStages in riff-raff.yaml is a list of 1? Should that be treated the same as a PROD stage, where we're discouraged from deploying a non-main branch to it?

That is should the logic be:

• If allowedStages is one item, do not comment
• If allowedStages has multiple items, remove PROD, sort alphabetically, comment using the first value

[tjsilver]

Wonder what the behaviour should be if allowedStages in riff-raff.yaml is a list of 1? Should that be treated the same as a PROD stage, where we're discouraged from deploying a non-main branch to it?

That is should the logic be:

* If `allowedStages` is one item, do not comment

* If `allowedStages` has multiple items, remove `PROD`, sort alphabetically, comment using the first value

That sounds sensible to me.