Apply abortOnCancel in JettyClientHttpConnector

This new option allows a cancel signal to abort the request, which is
how we expect a connection to be aborted in a reactive chain that
involves the WebClient.

Closes gh-26287

Author: rstoyanchev

spring-web/src/main/java/org/springframework/http/client/reactive/JettyClientHttpConnector.java

@@ -123,7 +123,7 @@ public Mono<ClientHttpResponse> connect(HttpMethod method, URI uri,
 		Request request = this.httpClient.newRequest(uri).method(method.toString());
 
 		return requestCallback.apply(new JettyClientHttpRequest(request, this.bufferFactory))
-				.then(Mono.fromDirect(ReactiveRequest.newBuilder(request).build()
+				.then(Mono.fromDirect(ReactiveRequest.newBuilder(request).abortOnCancel(true).build()
 						.response((reactiveResponse, chunkPublisher) -> {
 							Flux<DataBuffer> content = Flux.from(chunkPublisher).map(this::toDataBuffer);
 							return Mono.just(new JettyClientHttpResponse(reactiveResponse, content));