tests: remove snippets with inner attrs on non-block expressions

Author: calebcartwright

Diff for: rust-toolchain

@@ -1,3 +1,3 @@
 [toolchain]
-channel = "nightly-2021-05-01"
+channel = "nightly-2021-05-04"
 components = ["rustc-dev"]

Diff for: tests/source/match.rs

@@ -410,7 +410,7 @@ fn match_with_near_max_width() {
 
 fn match_with_trailing_spaces() {
     match x {    
-        #![allow(simple_match)]
+        
         Some(..) => 0,
         None => 1,
     }

Diff for: tests/target/issue-3592.rs

@@ -441,7 +441,6 @@ fn match_with_near_max_width() {
 
 fn match_with_trailing_spaces() {
     match x {
-        #![allow(simple_match)]
         Some(..) => 0,
         None => 1,
     }