InitializeUserDetailsBeanManagerConfigurer should respect primary flag

[quaff]

Expected Behavior
If one of multiple UserDetailsService beans is primary, then it should be configured.

Current Behavior
Warning log message instead.

spring-security/config/src/main/java/org/springframework/security/config/annotation/authentication/configuration/InitializeUserDetailsBeanManagerConfigurer.java

Lines 86 to 92 in c905ac3

	else if (beanNames.length > 1) {
	this.logger.warn(LogMessage.format("Found %s UserDetailsService beans, with names %s. "
	+ "Global Authentication Manager will not use a UserDetailsService for username/password login. "
	+ "Consider publishing a single UserDetailsService bean.", beanNames.length,
	Arrays.toString(beanNames)));
	return;
	}

Context

I want to enhance existing UserDetailsService like this:

    @Primary
    @Bean
    public UserDetailsService primaryUserDetailsService(UserDetailsService userDetailsService) {
        return (username) -> {
            // TODO load user from other source
            return userDetailsService.loadUserByUsername(username);
        };
    }

I'd like to contribute if it's accepted.