Delete R2dbcDatabaseInitializationConfiguration

The `R2dbcDatabaseInitializationConfiguration` docs class is not needed
in 2.5.x.

Closes gh-26225

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/howto/dataaccess/R2dbcDatabaseInitializationConfiguration.java

-/*
- * Copyright 2012-2021 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      https://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.springframework.boot.docs.howto.dataaccess;
-
-import io.r2dbc.spi.ConnectionFactory;
-
-import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.context.annotation.Configuration;
-import org.springframework.core.io.DefaultResourceLoader;
-import org.springframework.core.io.Resource;
-import org.springframework.core.io.ResourceLoader;
-import org.springframework.r2dbc.connection.init.ResourceDatabasePopulator;
-
-@Configuration(proxyBeanMethods = false)
-public class R2dbcDatabaseInitializationConfiguration {
-
-	@Autowired
-	public void initializeDatabase(ConnectionFactory connectionFactory) {
-		ResourceLoader resourceLoader = new DefaultResourceLoader();
-		Resource[] scripts = new Resource[] { resourceLoader.getResource("classpath:schema.sql"),
-				resourceLoader.getResource("classpath:data.sql") };
-		new ResourceDatabasePopulator(scripts).populate(connectionFactory).block();
-	}
-
-}