Remove redundant validation for redirect-uri

[jgrandja]

The OAuth 2.0 implementations of AuthenticationProvider and ReactiveAuthenticationManager perform an exact match on OAuth2AuthorizationRequest.getRedirectUri() and OAuth2AuthorizationResponse.getRedirectUri(), which is redundant given that the exact matching is also happening in the associated Filter and WebFilter.

We should remove this double validation since the check will always pass if the AuthenticationProvider or ReactiveAuthenticationManager is called.