Signals: Port connect calls to use callable_mp

Remove now unnecessary bindings of signal callbacks in the public API.
There might be some false positives that need rebinding if they were
meant to be public.

No regular expressions were harmed in the making of this commit.
(Nah, just kidding.)

modules/visual_script/visual_script_nodes.cpp

@@ -3130,8 +3130,6 @@ void VisualScriptCustomNode::_bind_methods() {
 	stepmi.return_val.usage |= PROPERTY_USAGE_NIL_IS_VARIANT;
 	BIND_VMETHOD(stepmi);
 
-	ClassDB::bind_method(D_METHOD("_script_changed"), &VisualScriptCustomNode::_script_changed);
-
 	BIND_ENUM_CONSTANT(START_MODE_BEGIN_SEQUENCE);
 	BIND_ENUM_CONSTANT(START_MODE_CONTINUE_SEQUENCE);
 	BIND_ENUM_CONSTANT(START_MODE_RESUME_YIELD);
@@ -3144,7 +3142,7 @@ void VisualScriptCustomNode::_bind_methods() {
 }
 
 VisualScriptCustomNode::VisualScriptCustomNode() {
-	connect_compat("script_changed", this, "_script_changed");
+	connect("script_changed", callable_mp(this, &VisualScriptCustomNode::_script_changed));
 }
 
 //////////////////////////////////////////