refactor(rustdoc): Remove redundant langstr checks

These same checks feed into `doctest.can_be_merged`,
making them redundant.

Author: epage

src/librustdoc/doctest.rs

@@ -1016,9 +1016,6 @@ impl CreateRunnableDocTests {
             .span(scraped_test.span)
             .build(dcx);
         let is_standalone = !doctest.can_be_merged
-            || scraped_test.langstr.compile_fail
-            || scraped_test.langstr.test_harness
-            || scraped_test.langstr.standalone_crate
             || self.rustdoc_options.nocapture
             || self.rustdoc_options.test_args.iter().any(|arg| arg == "--show-output");
         if is_standalone {