fixing remove button behaviour in Authentication settings

[patrickhafner]

On "authentication settings" page (/firewall/panel/security/authentication/) entries can not be removed. The POST params check fails, because following attributes are empty:

• url
• user
• pass

Also the checkPostParamsExist function will fail if the value to be checked is "0" or 0 regarding php documentation:

The following values are considered to be empty:

"" (an empty string) 0 (0 as an integer) 0.0 (0 as a float) "0" (0 as a string) ...

From https://www.php.net/manual/en/function.empty.php

[github-actions[bot]]

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