Switch some more Steps to builder.msg

In particular, this hides compiletest suites under a dropdown - some builders are configured with `verbose-tests`, which makes the suites take up many thousands of lines.

before:
```
Documenting stage1 cargo (x86_64-unknown-linux-gnu)
Check compiletest suite=rustdoc-js mode=js-doc-test (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
```

after:
```
::group::Documenting stage1 cargo (x86_64-unknown-linux-gnu)
::group::Testing stage1 compiletest suite=rustdoc-js mode=js-doc-test (x86_64-unknown-linux-gnu)
```

src/bootstrap/doc.rs

@@ -222,7 +222,7 @@ impl Step for TheBook {
         let shared_assets = builder.ensure(SharedAssets { target });
 
         // build the redirect pages
-        builder.info(&format!("Documenting book redirect pages ({})", target));
+        builder.msg_doc(compiler, "book redirect pages", target);
         for file in t!(fs::read_dir(builder.src.join(&relative_path).join("redirects"))) {
             let file = t!(file);
             let path = file.path();
@@ -306,7 +306,7 @@ impl Step for Standalone {
     fn run(self, builder: &Builder<'_>) {
         let target = self.target;
         let compiler = self.compiler;
-        builder.info(&format!("Documenting standalone ({})", target));
+        builder.msg_doc(compiler, "standalone", target);
         let out = builder.doc_out(target);
         t!(fs::create_dir_all(&out));
 
@@ -562,7 +562,7 @@ fn doc_std(
 
     let description =
         format!("library{} in {} format", crate_description(&requested_crates), format.as_str());
-    let _guard = builder.msg(Kind::Doc, stage, &description, compiler.host, target);
+    let _guard = builder.msg_doc(compiler, &description, target);
 
     let target_doc_dir_name = if format == DocumentationFormat::JSON { "json-doc" } else { "doc" };
     let target_dir =
@@ -804,14 +804,7 @@ macro_rules! tool_doc {
                     SourceType::Submodule
                 };
 
-                builder.info(
-                    &format!(
-                        "Documenting stage{} {} ({})",
-                        stage,
-                        stringify!($tool).to_lowercase(),
-                        target,
-                    ),
-                );
+                builder.msg_doc(compiler, stringify!($tool).to_lowercase(), target);
 
                 // Symlink compiler docs to the output directory of rustdoc documentation.
                 let out_dirs = [

src/bootstrap/lib.rs

@@ -1009,6 +1009,15 @@ impl Build {
         self.msg(Kind::Check, self.config.stage, what, self.config.build, target)
     }
 
+    fn msg_doc(
+        &self,
+        compiler: Compiler,
+        what: impl Display,
+        target: impl Into<Option<TargetSelection>> + Copy,
+    ) -> Option<gha::Group> {
+        self.msg(Kind::Doc, compiler.stage, what, compiler.host, target.into())
+    }
+
     fn msg_build(
         &self,
         compiler: Compiler,

src/bootstrap/test.rs

@@ -1832,11 +1832,13 @@ note: if you're sure you want to do this, please open an issue as to why. In the
             builder,
         );
 
-        builder.info(&format!(
-            "Check compiletest suite={} mode={} ({} -> {})",
-            suite, mode, &compiler.host, target
-        ));
-        let _time = util::timeit(&builder);
+        let _group = builder.msg(
+            Kind::Test,
+            compiler.stage,
+            &format!("compiletest suite={suite} mode={mode}"),
+            compiler.host,
+            target,
+        );
         crate::render_tests::try_run_tests(builder, &mut cmd, false);
 
         if let Some(compare_mode) = compare_mode {