scs: remove deprecated DerivedDataType::FSNODE_OLD

Summary:
This was not done until now because we needed to make sure no client depended on the old value anymore.

That is now the case.

Reviewed By: RajivTS

Differential Revision: D54310433

fbshipit-source-id: f17daa139b1be91a6f4a54e1d59b8f72a13066ce

eden/mononoke/scs/if/source_control.thrift

@@ -1067,9 +1067,6 @@ struct RepoLandStackParams {
 /// See https://www.internalfb.com/code/fbsource/[f84d7f31d5e251d6b1a4dcacce880e4b29a73652]/fbcode/eden/mononoke/derived_data/remote/if/derived_data_service.thrift?lines=40
 /// for an exhaustive list of derived data types.  For convenience, keep the variant numbers matching.
 enum DerivedDataType {
-  /// Derive fsnode data
-  /// DEPRECATED: Thrift enums should not start at 0.
-  FSNODE_OLD = 0,
   /// Derive fsnode data
   FSNODE = 1,
   /// Derive skeleton manifest data

eden/mononoke/scs_server/src/from_request.rs

@@ -381,9 +381,7 @@ impl FromRequest<thrift::DateTime> for DateTime<FixedOffset> {
 impl FromRequest<thrift::DerivedDataType> for DerivableType {
     fn from_request(data_type: &thrift::DerivedDataType) -> Result<Self, thrift::RequestError> {
         match *data_type {
-            thrift::DerivedDataType::FSNODE | thrift::DerivedDataType::FSNODE_OLD => {
-                Ok(DerivableType::Fsnodes)
-            }
+            thrift::DerivedDataType::FSNODE => Ok(DerivableType::Fsnodes),
             thrift::DerivedDataType::SKELETON_MANIFEST => Ok(DerivableType::SkeletonManifests),
             val => Err(errors::invalid_request(format!(
                 "unsupported derived data type ({})",