Remove remaining code that was deprecated in 2.5

Closes gh-30442

Author: wilkinsona

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jdbc/DataSourceAutoConfiguration.java

@@ -52,14 +52,11 @@
  * @author Kazuki Shimizu
  * @since 1.0.0
  */
-@SuppressWarnings("deprecation")
 @AutoConfiguration(before = SqlInitializationAutoConfiguration.class)
 @ConditionalOnClass({ DataSource.class, EmbeddedDatabaseType.class })
 @ConditionalOnMissingBean(type = "io.r2dbc.spi.ConnectionFactory")
 @EnableConfigurationProperties(DataSourceProperties.class)
-@Import({ DataSourcePoolMetadataProvidersConfiguration.class,
-		DataSourceInitializationConfiguration.InitializationSpecificCredentialsDataSourceInitializationConfiguration.class,
-		DataSourceInitializationConfiguration.SharedCredentialsDataSourceInitializationConfiguration.class })
+@Import(DataSourcePoolMetadataProvidersConfiguration.class)
 public class DataSourceAutoConfiguration {
 
 	@Configuration(proxyBeanMethods = false)