Remove ignored type alias test

This is tracked by a GH issue 17164, and having an ignored test for it isn't
helpful.

src/test/ui/fully-qualified-type/fully-qualified-type-name3.rs

@@ -1,14 +0,0 @@
-// Test that we use fully-qualified type names in error messages.
-
-// ignore-test
-
-type T1 = usize;
-type T2 = isize;
-
-fn bar(x: T1) -> T2 {
-    return x;
-    //~^ ERROR mismatched types: expected `T2`, found `T1`
-}
-
-fn main() {
-}