remove code duplication when hashing query result and interning node

Refactored the duplicated code into a function.

`with_feed_task` currently passes the query key to `debug_assert!`.
This commit changes that, so it debug prints the `DepNode`, as in
`with_task`.

compiler/rustc_middle/src/query/plumbing.rs

@@ -548,7 +548,6 @@ macro_rules! define_feedable {
                         let dep_node_index = tcx.dep_graph.with_feed_task(
                             dep_node,
                             tcx,
-                            key,
                             &value,
                             hash_result!([$($modifiers)*]),
                         );