tests: Move run-pass tests without naming conflicts to ui

src/test/ui/array-slice-vec/array_const_index-1.rs

@@ -0,0 +1,12 @@
+// run-pass
+#![allow(dead_code)]
+#![allow(stable_features)]
+
+#![feature(const_indexing)]
+
+fn main() {
+    const ARR: [i32; 6] = [42, 43, 44, 45, 46, 47];
+    const IDX: usize = 3;
+    const VAL: i32 = ARR[IDX];
+    const BLUB: [i32; (ARR[0] - 41) as usize] = [5];
+}