remove PredecessorDependencies from RootDirectoryBranchClusterManifestId BonsaiDerivable impl

Summary: This is no longer part of `BonsaiDerivable` as it was moved to a separate trait.

Reviewed By: lmvasquezg

Differential Revision: D93488915

fbshipit-source-id: 662eb82606e063846b1fe6365388415e1f750fcd

Author: YousefSalama

eden/mononoke/derived_data/directory_branch_cluster_manifest/mapping.rs

@@ -77,7 +77,6 @@ impl BonsaiDerivable for RootDirectoryBranchClusterManifestId {
     const VARIANT: DerivableType = DerivableType::DirectoryBranchClusterManifest;
 
     type Dependencies = dependencies![RootSkeletonManifestV2Id];
-    type PredecessorDependencies = dependencies![];
 
     async fn derive_single(
         ctx: &CoreContext,