Remove absolute URI check from ReactorClientHttpConnector

This allows maknig use of the Unix Domain Socket support in Reactor 1.0.

Closes spring-projectsgh-25929

Author: hitchan

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

@@ -100,10 +100,6 @@ public ReactorClientHttpConnector(HttpClient httpClient) {
 	public Mono<ClientHttpResponse> connect(HttpMethod method, URI uri,
 			Function<? super ClientHttpRequest, Mono<Void>> requestCallback) {
 
-		if (!uri.isAbsolute()) {
-			return Mono.error(new IllegalArgumentException("URI is not absolute: " + uri));
-		}
-
 		AtomicReference<ReactorClientHttpResponse> responseRef = new AtomicReference<>();
 
 		return this.httpClient