Freeze configuration before invoking MBDPP instances

This commit updates refresh for AOT processing so that the configuration
is frozen before invoking MergedBeanDefinitionPostProcessor instances.
This makes sure that post-processed MergedBeanDefinitions are kept in
cache and not lost if a component attempts to clear the metadata cache.

Closes gh-28941

spring-context/src/test/java/org/springframework/context/support/GenericApplicationContextTests.java

@@ -409,6 +409,19 @@ class GenericApplicationContextTests {
 		context.close();
 	}
 
+	@Test
+	void refreshForAotFreezeConfiguration() {
+		GenericApplicationContext context = new GenericApplicationContext();
+		context.registerBeanDefinition("test", new RootBeanDefinition(String.class));
+		MergedBeanDefinitionPostProcessor bpp = registerMockMergedBeanDefinitionPostProcessor(context);
+		context.refreshForAotProcessing();
+		RootBeanDefinition mergedBeanDefinition = getBeanDefinition(context, "test");
+		verify(bpp).postProcessMergedBeanDefinition(mergedBeanDefinition, String.class, "test");
+		context.getBeanFactory().clearMetadataCache();
+		assertThat(context.getBeanFactory().getMergedBeanDefinition("test")).isSameAs(mergedBeanDefinition);
+		context.close();
+	}
+
 	@Test
 	void refreshForAotInvokesBeanPostProcessorContractOnMergedBeanDefinitionPostProcessors() {
 		MergedBeanDefinitionPostProcessor bpp = new MergedBeanDefinitionPostProcessor() {