Rollup merge of #50806 - oli-obk:gesundheit, r=ehuss

Add `bless` x.py subcommand for easy ui test replacement

fixes #49815

r? @nikomatsakis

src/bootstrap/builder.rs

@@ -1460,6 +1460,7 @@ mod __test {
             rustc_args: vec![],
             fail_fast: true,
             doc_tests: DocTests::No,
+            bless: false,
         };
 
         let build = Build::new(config);