test: audit recursion tests

Author: Embers-of-the-Fire

tests/ui/recursion/future-stream-buffer-unordered-40003.rs

@@ -1,4 +1,4 @@
-//@ run-pass
+//@ build-pass
 #![allow(unused_must_use)]
 fn main() {
     if false { test(); }

tests/ui/recursion/instantiable.rs

@@ -1,4 +1,4 @@
-//@ run-pass
+//@ build-pass
 
 #![allow(non_camel_case_types)]
 #![allow(dead_code)]

tests/ui/recursion/recursive-enum-box.rs

@@ -1,4 +1,4 @@
-//@ run-pass
+//@ build-pass
 // A smoke test for recursive enum structures using Box<T>.
 // This test constructs a linked list-like structure to exercise memory allocation and ownership.
 // Originally introduced in 2010, this is one of Rust’s earliest test cases.