Remove WebClient's in-memory buffer size limit for endpoint tests

Previously, the endpoints' responses could occasionally exceed
WebClient's in-memory buffer limt, for example if the threads endpoint
was reporting a large number of threads or the threads had large
stacks.

This commit disables WebClient's in-memory buffer size limit so that
the tests passing is not dependent on the size of the endpoints'
responses.

Closes gh-22743

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/integrationtest/WebMvcEndpointExposureIntegrationTests.java

@@ -166,7 +166,7 @@ class WebMvcEndpointExposureIntegrationTests {
 		int port = context.getSourceApplicationContext(ServletWebServerApplicationContext.class).getWebServer()
 				.getPort();
 		ExchangeStrategies exchangeStrategies = ExchangeStrategies.builder()
-				.codecs((configurer) -> configurer.defaultCodecs().maxInMemorySize(512 * 1024)).build();
+				.codecs((configurer) -> configurer.defaultCodecs().maxInMemorySize(-1)).build();
 		return WebTestClient.bindToServer().baseUrl("http://localhost:" + port).exchangeStrategies(exchangeStrategies)
 				.build();
 	}