Delete duplicate test from AutoDiff/SILOptimizer/generics.swift

It's already included in test/AutoDiff/SILOptimizer/fragile_curry_thunk.swift

Author: kovdan01

test/AutoDiff/SILOptimizer/generics.swift

@@ -250,27 +250,6 @@ extension TF_682_Proto where Self : Differentiable,
   }
 }
 
-// NOTE(TF-1208): Differentiation regression due to changes in curry thunk generation.
-/*
-// TF-688: Test generic curry thunk cloning.
-public struct TF_688_Struct<Scalar> {
-  var x: Scalar
-}
-extension TF_688_Struct: Differentiable where Scalar: Differentiable {
-  @differentiable(reverse)
-  public static func id(x: Self) -> Self {
-    return x
-  }
-}
-@differentiable(reverse, wrt: x)
-public func TF_688<Scalar: Differentiable>(
-  _ x: TF_688_Struct<Scalar>,
-  reduction: @differentiable(reverse) (TF_688_Struct<Scalar>) -> TF_688_Struct<Scalar> = TF_688_Struct.id
-) -> TF_688_Struct<Scalar> {
-  reduction(x)
-}
-*/
-
 // TF-697: Test generic requirements of generated derivative function.
 protocol TF_697_Module: Differentiable {
     associatedtype Input