Avoid using OkHttp3ClientHttpRequestFactory in test

See spring-projectsgh-40611

spring-boot-project/spring-boot-test/src/test/java/org/springframework/boot/test/web/client/TestRestTemplateTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -94,7 +94,7 @@ void doNotReplaceCustomRequestFactory() {
 
 	@Test
 	void useTheSameRequestFactoryClassWithBasicAuth() {
-		OkHttp3ClientHttpRequestFactory customFactory = new OkHttp3ClientHttpRequestFactory();
+		TestClientHttpRequestFactory customFactory = new TestClientHttpRequestFactory();
 		RestTemplateBuilder builder = new RestTemplateBuilder().requestFactory(() -> customFactory);
 		TestRestTemplate testRestTemplate = new TestRestTemplate(builder).withBasicAuth("test", "test");
 		RestTemplate restTemplate = testRestTemplate.getRestTemplate();
@@ -386,4 +386,8 @@ interface TestRestTemplateCallback {
 
 	}
 
+	static class TestClientHttpRequestFactory extends SimpleClientHttpRequestFactory {
+
+	}
+
 }