Before, Spring Security's @Enable* annotations were meta-annotated with @Configuration.
While convenient, this is not consistent with the rest of the Spring projects and most notably
Spring Framework's @Enable annotations. Additionally, the introduction of support for
@Configuration(proxyBeanMethods=false) in Spring Framework provides a compelling reason to
remove @Configuration meta-annotation from Spring Security's @Enable annotations and allow
users to opt into their preferred configuration mode.
Closes gh-6613
Signed-off-by: Joshua Sattler <joshua.sattler@mailbox.org>