Replace deprecated schema URL construction in OhInfXmlValidationCheck

[Copilot]

This PR addresses the linked review comment requesting the Java 21 URL deprecation fix in production code (not only in tests).
The OhInfXmlValidationCheck schema download path now avoids new URL(String) while preserving existing behavior and error handling intent.

• Production deprecation fix

  • Updated schema URL creation in getXSD(...) from deprecated new URL(schemaUrlString) to URI.create(schemaUrlString).toURL().

• Error-path compatibility

  • Extended the existing catch block to include IllegalArgumentException (thrown by URI.create(...)) alongside IOException, so invalid schema strings are still handled via the same logging/null fallback path.

URL schemaUrl = URI.create(schemaUrlString).toURL();
return client.get(schemaUrl);

[wborn]

Thank you for your efforts.