chore!(config): prevent multiline env var interpolation (#24088)

* chore!(config): prevent multiline env var interpolation

* changelog too verbose

* add doc example

* trailing

* update deprecations.md

* add author

* clippy fix

* Update website/content/en/docs/reference/environment_variables.md

Co-authored-by: May Lee <mayl@alumni.cmu.edu>

---------

Co-authored-by: May Lee <mayl@alumni.cmu.edu>