[Security] 4.3 Always "Bad credentials." with algorithm "auto"

**Symfony version(s) affected**: 4.3.0

**Description**  
Previosly encoded password becomes invalid. All of them started with "$2y$13$" which means "bcrypt wit cost 13" I think.

**How to reproduce**  
Create user with "bcrypt" password encoder, change encoder to "auto" and try to login.

**Additional context**  
I use doctrine entity user provider.
PHP 7.2.17 no sodium installed
