Improve PAT expiration validation error messages

What does this MR do and why?

• Follow-up from previous MR
• #410965 (closed)

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Before	After

How to set up and validate locally

1. Create a PAT with an expiration date more than 365 days in the future

      PersonalAccessToken.create!(expires_at: 2.years.from_now, user:User.last, scopes: ['api'])

2. See a beautiful error message

   ActiveRecord::RecordInvalid: Validation failed: Expiration date must be before 2024-06-15 05:12:08 UTC

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.