fix(schema): always pass raw string value to error validators, only trim to 30 chars for maxlength validator

[vkarpov15]

Fix #16236
Re: #15550
Re: #15571

Summary

Original bug report was about trimming long strings in the maxlength validator, but the fix in #15571 also leaks the 30 character max limit to user-specified validators, which is incorrect. With this PR, the validator props will always have the raw untrimmed value, and we will just apply the 30 character limit to the error message for the maxlength validator.

Examples

[Copilot]

Pull request overview

Fixes a regression introduced by #15571 where string values in props.value were truncated for all validators, by ensuring validator props always carry the raw value and limiting truncation to maxlength error message formatting.

Changes:

• Stop truncating validatorProperties.value in SchemaType#doValidate() and #doValidateSync().
• Add targeted truncation logic for maxlength message formatting in SchemaString.
• Add/extend tests asserting err.errors.*.value and properties.value remain untrimmed, including for custom validator message functions.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
lib/schemaType.js	Removes global string truncation from validator properties so custom validators see full values.
lib/schema/string.js	Wraps maxlength validator message formatting to trim displayed value while keeping stored values raw.
test/schema.validation.test.js	Adds coverage to ensure custom validator message functions receive full string values (async + sync).
test/errors.validation.test.js	Adds assertions that maxlength validation errors keep full value/properties.value while message remains trimmed.

[hasezoey]

Considering that the following if also added a typeof == "string" check and is followed by a unconditional call to formatMessage, this seems unnecessary; unless it is necessary for performance?