Rollup merge of #109629 - aliemjay:remove-givens, r=lcnr

remove obsolete `givens` from regionck

Revives #107376. The only change is the last commit (2a3177a8bc) which should fix the regression.

Fixes https://github.com/rust-lang/rust/issues/106567

r? `@lcnr`

compiler/rustc_infer/src/infer/mod.rs

@@ -869,10 +869,6 @@ impl<'tcx> InferCtxt<'tcx> {
         self.inner.borrow().undo_log.opaque_types_in_snapshot(&snapshot.undo_snapshot)
     }
 
-    pub fn add_given(&self, sub: ty::Region<'tcx>, sup: ty::RegionVid) {
-        self.inner.borrow_mut().unwrap_region_constraints().add_given(sub, sup);
-    }
-
     pub fn can_sub<T>(&self, param_env: ty::ParamEnv<'tcx>, a: T, b: T) -> bool
     where
         T: at::ToTrace<'tcx>,