v.25.10Improvement

Check credentials in the Web UI only

Check credentials in the Web UI only on pasting, rather than on every key press. This avoids a problem with misconfigured LDAP servers. This closes #85777. #88769 (Alexey Milovidov).
Modify the Web UI to validate credentials only when they are pasted, rather than on every key press.

Why it matters

This change addresses an issue with misconfigured LDAP servers by reducing unnecessary authentication checks on each key press, improving performance and user experience during login.

How to use it

No user action is required. The Web UI now automatically performs credential validation only upon pasting input into the login fields.