Move const generic regression tests to their old folder

src/test/ui/const-generics/issues/issue-60818-struct-constructors.rs

@@ -0,0 +1,10 @@
+// build-pass (FIXME(62277): could be check-pass?)
+
+#![feature(const_generics)]
+//~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash
+
+struct Generic<const V: usize>;
+
+fn main() {
+    let _ = Generic::<0>;
+}