Revert "Auto merge of #113166 - moulins:ref-niches-initial, r=oli-obk"

This reverts commit 557359f925, reversing
changes made to 1e6c09a803.

compiler/rustc_session/src/config.rs

@@ -3117,7 +3117,6 @@ pub(crate) mod dep_tracking {
     use rustc_feature::UnstableFeatures;
     use rustc_span::edition::Edition;
     use rustc_span::RealFileName;
-    use rustc_target::abi::ReferenceNichePolicy;
     use rustc_target::spec::{CodeModel, MergeFunctions, PanicStrategy, RelocModel};
     use rustc_target::spec::{
         RelroLevel, SanitizerSet, SplitDebuginfo, StackProtector, TargetTriple, TlsModel,
@@ -3213,7 +3212,6 @@ pub(crate) mod dep_tracking {
         OomStrategy,
         LanguageIdentifier,
         TraitSolver,
-        ReferenceNichePolicy,
     );
 
     impl<T1, T2> DepTrackingHash for (T1, T2)