chore(spring): set proxyBeanMethods=false on Vaadin Spring config classes

[torsten-liermann]

Summary

VaadinApplicationConfiguration and SpringBootAutoConfiguration
declare @Configuration without an explicit proxyBeanMethods
setting, which defaults to true. Neither class self-cross-references
its own @Bean methods, and neither uses @Transactional,
@Async or other AOP that requires the configuration self-proxy —
so the CGLIB-enhancement step that the default brings is dead weight.

Setting proxyBeanMethods = false on both classes drops that
enhancement step. Per Spring's own
@Configuration Javadoc,
this is the recommended setting whenever @Bean cross-references
are not in use.

Diff

-@Configuration
+@Configuration(proxyBeanMethods = false)
 public class VaadinApplicationConfiguration {

-@Configuration
+@Configuration(proxyBeanMethods = false)
 public class SpringBootAutoConfiguration {

Why this matters in practice

In a Jakarta EE FAT-EAR with multiple Vaadin-bearing WARs deployed
in parallel on WildFly / JBoss EAP, each WAR drives its own Spring
ApplicationContext through these two classes concurrently. Their
CGLIB-enhancement stage races on the JBoss-Modules class-loader
lock and produces a deployment hang. Removing the proxy (which is
unused) removes the contention.

Intentionally not changed

VaadinServletConfiguration (imported via @Import from
SpringBootAutoConfiguration) really does have a self
cross-reference: vaadinRootMapping directly invokes
vaadinForwardingController(). That class needs the @Bean
self proxy and is left untouched.

Risk

Minimal. The change is local to two configuration classes that
do not exercise the proxy semantics. Subclasses with custom
@Bean self-cross-references would need their own
proxyBeanMethods = true — none such exist upstream.

[cla-assistant]

All committers have signed the CLA.