Fix cli options (sigp#4772)

## Issue Addressed

Fixes breaking change introduced on sigp#4674  that doesn't allow multiple `http_enabled` `ArgGroup` flags

Author: jxs

beacon_node/src/cli.rs

@@ -1315,5 +1315,5 @@ pub fn cli_app<'a, 'b>() -> App<'a, 'b> {
                 .default_value("64")
                 .takes_value(true)
         )
-        .group(ArgGroup::with_name("enable_http").args(&["http", "gui", "staking"]))
+        .group(ArgGroup::with_name("enable_http").args(&["http", "gui", "staking"]).multiple(true))
 }

lighthouse/tests/beacon_node.rs

@@ -2376,6 +2376,18 @@ fn gui_flag() {
         });
 }
 
+#[test]
+fn multiple_http_enabled_flags() {
+    CommandLineTest::new()
+        .flag("gui", None)
+        .flag("http", None)
+        .flag("staking", None)
+        .run_with_zero_port()
+        .with_config(|config| {
+            assert!(config.http_api.enabled);
+        });
+}
+
 #[test]
 fn optimistic_finalized_sync_default() {
     CommandLineTest::new()