* api-gateway: add operation cannot be fulfilled error to common errors (#17874)

* add error message

* Update website/content/docs/api-gateway/usage/errors.mdx

Co-authored-by: Nathan Coleman <[email protected]>

* fix formating issues

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Co-authored-by: Nathan Coleman <[email protected]>

* api-gateway: add step to upgrade instructions for creating intentions (#17875)

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Co-authored-by: sarahalsmiller <[email protected]>