Increase password characters limit during login

- allow logging in with longer passwords, for example tokens generated
by AWS RDS IAM authentication

- show error message when the limit is reached instead of silently
trimming the password to avoid confusion

Signed-off-by: Kamil Hristov <kamilhristov@gmail.com>

libraries/classes/Plugins/Auth/AuthenticationCookie.php

@@ -335,8 +335,11 @@ class AuthenticationCookie extends AuthenticationPlugin
             $this->user = Core::sanitizeMySQLUser($_POST['pma_username']);
 
             $password = $_POST['pma_password'] ?? '';
-            if (strlen($password) > 256) {
-                $password = substr($password, 0, 256);
+            if (strlen($password) > 1000) {
+                $conn_error = __('Your password is too long. To prevent denial-of-service attacks, ' .
+                    'phpMyAdmin restricts passwords to less than 1000 characters.');
+
+                return false;
             }
             $this->password = $password;