Don't include bang in macro replacement suggestion

When we suggest the replacement for a macro we include the "!" in the
suggested replacement but the span only contains the name of the macro
itself. Using that replacement would cause a duplicate "!" in the
resulting code.

I originally tried to extend the span to be replaced by 1 byte in
rust-lang/rust#47424. However, @zackmdavis pointed out that there can be
whitespace between the macro name and the bang.

Instead, just remove the bang from the suggested replacement.

Fixes #47418

src/test/ui/macros/macro-name-typo.stderr

@@ -2,7 +2,7 @@ error: cannot find macro `printlx!` in this scope
   --> $DIR/macro-name-typo.rs:12:5
    |
 12 |     printlx!("oh noes!"); //~ ERROR cannot find
-   |     ^^^^^^^ help: you could try the macro: `println!`
+   |     ^^^^^^^ help: you could try the macro: `println`
 
 error: aborting due to previous error
 

src/test/ui/macros/macro_undefined.stderr

@@ -10,7 +10,7 @@ error: cannot find macro `k!` in this scope
   --> $DIR/macro_undefined.rs:21:5
    |
 21 |     k!(); //~ ERROR cannot find
-   |     ^ help: you could try the macro: `kl!`
+   |     ^ help: you could try the macro: `kl`
 
 error: aborting due to 2 previous errors