Document new behaviour for init resource with source integrations

[mariadelpilargomezmoya-ops]

Offering

Upsun Flex

What needs to be documented?

we are changing the default values of init resources for source integrations to match the ones we have without source integrations.
PR here: #5640 still a draft, we can't publish until it has been rolled out.
Note, the changes only affect the API for now and default behavior. CLI and Console will likely need to work on properly supporting different values per-environment, but the API is backwards compatible.

Docs impact

Get started materials or framework-specific guides

Optional: Additional context

see draft PR