Drop this in error message to not reach 100 characters

Author: kper

src/librustc_parse/lexer/tokentrees.rs

@@ -246,7 +246,7 @@ impl<'a> TokenTreesReader<'a> {
                             if (parent.0.to(parent.1)).contains(span) {
                                 err.span_label(
                                     span,
-                                    "this block is empty, you might have not meant to close it",
+                                    "block is empty, you might have not meant to close it",
                                 );
                             }
                             else {

src/test/ui/parser/issue-70583-block-is-empty-2.rs

@@ -7,7 +7,7 @@ impl ErrorHandled {
     pub fn assert_reported(self) {
         match self {
             ErrorHandled::Reported => {}}
-                                     //^~ ERROR this block is empty, you might have not meant to close it
+                                     //^~ ERROR block is empty, you might have not meant to close it
             ErrorHandled::TooGeneric => panic!(),
         }
     }

src/test/ui/parser/issue-70583-block-is-empty-2.stderr

@@ -2,7 +2,7 @@ error: unexpected closing delimiter: `}`
   --> $DIR/issue-70583-block-is-empty-2.rs:14:1
    |
 LL |             ErrorHandled::Reported => {}}
-   |                                       -- this block is empty, you might have not meant to close it
+   |                                       -- block is empty, you might have not meant to close it
 ...
 LL | }
    | ^ unexpected closing delimiter