fix: #3589845 Do not log missing form ID when the image CAPTCHA was not built

Jakob Prequested to merge
issue/captcha-3589845:3589845-missing-required-form into 2.x

A #limit_validation_errors submission, such as a managed_file upload, leaves the CAPTCHA element unprocessed, so it has no #captcha_info. The image CAPTCHA #process callback logged "Missing required form ID on route ..." on every such request. Only log when an image was built without a form ID.

Closes #3589845

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