Rollup merge of #120693 - nnethercote:invert-diagnostic-lints, r=davidtwco

Invert diagnostic lints.

That is, change `diagnostic_outside_of_impl` and `untranslatable_diagnostic` from `allow` to `deny`, because more than half of the compiler has been converted to use translated diagnostics.

This commit removes more `deny` attributes than it adds `allow` attributes, which proves that this change is warranted.

r? ````@davidtwco````

compiler/rustc_hir_pretty/src/lib.rs

@@ -2,8 +2,6 @@
 //! the definitions in this file have equivalents in `rustc_ast_pretty`.
 
 #![recursion_limit = "256"]
-#![deny(rustc::untranslatable_diagnostic)]
-#![deny(rustc::diagnostic_outside_of_impl)]
 
 use rustc_ast as ast;
 use rustc_ast::util::parser::{self, AssocOp, Fixity};