Replace lightning-block-sync test that depended on foo.com

Our tests should generally not rely on internet access, and should
not rely on the behavior of any given remote server. However, one
of the `endpoint_tests` in `lightning-block-sync::http` relied on
`foo.com` resolving to a single socket address, which both might
change in the future and makes our tests fail without internet.

Author: TheBlueMatt

lightning-block-sync/src/http.rs

@@ -511,21 +511,19 @@ mod endpoint_tests {
 
 	#[test]
 	fn convert_to_socket_addrs() {
-		let endpoint = HttpEndpoint::for_host("foo.com".into());
+		let endpoint = HttpEndpoint::for_host("localhost".into());
 		let host = endpoint.host();
 		let port = endpoint.port();
 
 		use std::net::ToSocketAddrs;
 		match (&endpoint).to_socket_addrs() {
 			Err(e) => panic!("Unexpected error: {:?}", e),
-			Ok(mut socket_addrs) => {
-				match socket_addrs.next() {
-					None => panic!("Expected socket address"),
-					Some(addr) => {
-						assert_eq!(addr, (host, port).to_socket_addrs().unwrap().next().unwrap());
-						assert!(socket_addrs.next().is_none());
-					}
+			Ok(socket_addrs) => {
+				let mut std_addrs = (host, port).to_socket_addrs().unwrap();
+				for addr in socket_addrs {
+					assert_eq!(addr, std_addrs.next().unwrap());
 				}
+				assert!(std_addrs.next().is_none());
 			}
 		}
 	}