Revert OAuth2AuthorizationCodeGrantWebFilter works with /{action}/

Issue #5856
Commit 385bdfc055854581e9e9f671d11f86a978c27c42

NOTE: This commit 'partially' reverts #5856. Only the ServerWebExchangeMatcher for OAuth2LoginSpec is reverted.

Fixes gh-6890

config/src/main/java/org/springframework/security/config/web/server/ServerHttpSecurity.java

@@ -56,7 +56,6 @@ import org.springframework.security.core.Authentication;
 import org.springframework.security.core.AuthenticationException;
 import org.springframework.security.core.GrantedAuthority;
 import org.springframework.security.core.authority.AuthorityUtils;
-import org.springframework.security.core.context.ReactiveSecurityContextHolder;
 import org.springframework.security.core.userdetails.ReactiveUserDetailsService;
 import org.springframework.security.oauth2.client.InMemoryReactiveOAuth2AuthorizedClientService;
 import org.springframework.security.oauth2.client.ReactiveOAuth2AuthorizedClientService;
@@ -866,11 +865,7 @@ public class ServerHttpSecurity {
 		}
 
 		private ServerWebExchangeMatcher createAttemptAuthenticationRequestMatcher() {
-			PathPatternParserServerWebExchangeMatcher loginPathMatcher = new PathPatternParserServerWebExchangeMatcher("/login/oauth2/code/{registrationId}");
-			ServerWebExchangeMatcher notAuthenticatedMatcher = e  -> ReactiveSecurityContextHolder.getContext()
-					.flatMap(p -> ServerWebExchangeMatcher.MatchResult.notMatch())
-					.switchIfEmpty(ServerWebExchangeMatcher.MatchResult.match());
-			return new AndServerWebExchangeMatcher(loginPathMatcher, notAuthenticatedMatcher);
+			return new PathPatternParserServerWebExchangeMatcher("/login/oauth2/code/{registrationId}");
 		}
 
 		private ReactiveOAuth2UserService<OidcUserRequest, OidcUser> getOidcUserService() {