Remove obsolete RustcGuide bootstrap step

It was not working for a long time.

src/bootstrap/src/core/build_steps/test.rs

@@ -2525,35 +2525,6 @@ fn markdown_test(builder: &Builder<'_>, compiler: Compiler, markdown: &Path) ->
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
-pub struct RustcGuide;
-
-impl Step for RustcGuide {
-    type Output = ();
-    const DEFAULT: bool = false;
-    const ONLY_HOSTS: bool = true;
-
-    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
-        run.path("src/doc/rustc-dev-guide")
-    }
-
-    fn make_run(run: RunConfig<'_>) {
-        run.builder.ensure(RustcGuide);
-    }
-
-    fn run(self, builder: &Builder<'_>) {
-        let relative_path = "src/doc/rustc-dev-guide";
-        builder.require_submodule(relative_path, None);
-
-        let src = builder.src.join(relative_path);
-        let mut rustbook_cmd = builder.tool_cmd(Tool::Rustbook).delay_failure();
-        rustbook_cmd.arg("linkcheck").arg(&src);
-        let toolstate =
-            if rustbook_cmd.run(builder) { ToolState::TestPass } else { ToolState::TestFail };
-        builder.save_toolstate("rustc-dev-guide", toolstate);
-    }
-}
-
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct CrateLibrustc {
     compiler: Compiler,

src/bootstrap/src/core/builder/mod.rs

@@ -951,7 +951,6 @@ impl<'a> Builder<'a> {
                 test::UnstableBook,
                 test::RustcBook,
                 test::LintDocs,
-                test::RustcGuide,
                 test::EmbeddedBook,
                 test::EditionGuide,
                 test::Rustfmt,