Simplify HTTP compression support for Reactor Netty

This commit simplifies the HTTP compression configuration for Reactor
Netty servers.

Also, this commit removes a test for the
`server.compression.min-response-size` support, as this is only
supported when the HTTP response contains a `Content-Length` header.
Since most Spring WebFlux responses are using
`Transfer-Encoding: chunked`, we should not test for that case.

See gh-12268

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/netty/NettyReactiveWebServerFactory.java

@@ -106,8 +106,8 @@ public class NettyReactiveWebServerFactory extends AbstractReactiveWebServerFact
 						getSsl(), getSslStoreProvider());
 				sslServerCustomizer.customize(options);
 			}
-			if (getCompression() != null && getCompression().getEnabled()) {
+			if (getCompression() != null) {
-				options.compression(getCompression().getMinResponseSize());
+				options.compression(getCompression().getEnabled());
 			}
 			applyCustomizers(options);
 		}).build();

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/reactive/server/AbstractReactiveWebServerFactoryTests.java

@@ -273,19 +273,6 @@ public abstract class AbstractReactiveWebServerFactoryTests {
 		assertResponseIsCompressed(response);
 	}
 
-	@Test
-	public void noCompressionForSmallResponse() throws Exception {
-		Assumptions.assumeThat(getFactory())
-				.isInstanceOf(NettyReactiveWebServerFactory.class);
-		Compression compression = new Compression();
-		compression.setEnabled(true);
-		compression.setMinResponseSize(3001);
-		WebClient client = prepareCompressionTest(compression);
-		ResponseEntity<Void> response = client.get().exchange()
-				.flatMap((res) -> res.toEntity(Void.class)).block();
-		assertResponseIsNotCompressed(response);
-	}
-
 	@Test
 	public void noCompressionForMimeType() throws Exception {
 		Assumptions.assumeThat(getFactory())