Revert "Use workspace lints for crates in compiler/ #138084"

Revert <https://github.com/rust-lang/rust/pull/138084> to buy time to
consider options that avoids breaking downstream usages of cargo on
distributed `rustc-src` artifacts, where such cargo invocations fail due
to inability to inherit `lints` from workspace root manifest's
`workspace.lints` (this is only valid for the source rust-lang/rust
workspace, but not really the distributed `rustc-src` artifacts).

This breakage was reported in
<https://github.com/rust-lang/rust/issues/138304>.

This reverts commit 48caf81484, reversing
changes made to c6662879b2.

compiler/rustc_data_structures/src/graph/tests.rs

@@ -3,7 +3,7 @@ use std::cmp::max;
 use super::*;
 use crate::fx::FxHashMap;
 
-pub(super) struct TestGraph {
+pub struct TestGraph {
     num_nodes: usize,
     start_node: usize,
     successors: FxHashMap<usize, Vec<usize>>,
@@ -11,7 +11,7 @@ pub(super) struct TestGraph {
 }
 
 impl TestGraph {
-    pub(super) fn new(start_node: usize, edges: &[(usize, usize)]) -> Self {
+    pub fn new(start_node: usize, edges: &[(usize, usize)]) -> Self {
         let mut graph = TestGraph {
             num_nodes: start_node + 1,
             start_node,