Rollup merge of rust-lang#87098 - JohnTitor:unignore-some-tests, r=petrochenkov

Unignore some pretty printing tests

Closes rust-lang#37201
r? ```@petrochenkov```

Author: JohnTitor

src/test/ui/issues/issue-20427.rs

@@ -7,7 +7,6 @@
 #![allow(deprecated, deprecated_in_future)]
 
 // aux-build:i8.rs
-// ignore-pretty issue #37201
 
 extern crate i8;
 use std::string as i16;

src/test/ui/issues/issue-22992.rs

@@ -1,5 +1,4 @@
 // run-pass
-// ignore-pretty issue #37201
 
 struct X { val: i32 }
 impl std::ops::Deref for X {

src/test/ui/issues/issue-23338-ensure-param-drop-order.rs

@@ -1,8 +1,6 @@
 // run-pass
 #![allow(non_upper_case_globals)]
 
-// ignore-pretty issue #37201
-
 // This test is ensuring that parameters are indeed dropped after
 // temporaries in a fn body.
 

src/test/ui/issues/issue-27401-dropflag-reinit.rs

@@ -1,5 +1,4 @@
 // run-pass
-// ignore-pretty issue #37201
 
 // Check that when a `let`-binding occurs in a loop, its associated
 // drop-flag is reinitialized (to indicate "needs-drop" at the end of