chore(auth-service): [CHK-3743] update auth validate spec

[CianoDanilo]

List of changes

Removed 400 as a possible response code.

Motivation and context

Type of changes

• Add new resources
• Update configuration to existing resources
• Remove existing resources

Does this introduce a change to production resources with possible user impact?

• Yes, users may be impacted applying this change
• No

Does this introduce an unwanted change on infrastructure? Check terraform plan execution result

• Yes
• No

Other information

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If PR is partially applied, why? (reserved to mantainers)

[infantesimone]

Okay, remove the status code, but is it correct to expose this API on the APIM? Thinking about it, this API will only be used internally between APIM and the service, it is not used by checkout. I suggest removing this API from this group of APIs.

[CianoDanilo]

Okay, remove the status code, but is it correct to expose this API on the APIM? Thinking about it, this API will only be used internally between APIM and the service, it is not used by checkout. I suggest removing this API from this group of APIs.

Done in cf1aa15