remove suppression disablement workaround

Author: kavon

test/ModuleInterface/discard_interface.swift

@@ -8,7 +8,6 @@
 // CHECK: @_alwaysEmitIntoClient public consuming func AEIC_discard() { discard self }
 // CHECK: @inlinable public consuming func inlinable_discard() { discard self }
 
-@_disallowFeatureSuppression(NoncopyableGenerics)
 public struct MoveOnlyStruct: ~Copyable {
   let x = 0