Rollup merge of #111969 - clubby789:clean-dry-run, r=Mark-Simulacrum

bootstrap: Make `clean` respect `dry-run`

I noticed `clean_default` was getting run twice as the `DryRun::SelfCheck` flag is ignored

src/bootstrap/clean.rs

@@ -85,6 +85,10 @@ clean_crate_tree! {
 }
 
 fn clean_default(build: &Build, all: bool) {
+    if build.config.dry_run() {
+        return;
+    }
+
     rm_rf("tmp".as_ref());
 
     if all {