ARROW-15709: [C++] Revert change

This reverts commit afaa92e, as it seems it can have adverse effects on contributors' checkouts.

Closes #12454 from pitrou/revert-afaa92e7e4289d6e4f302cc91810368794e8092b

Authored-by: Antoine Pitrou <antoine@python.org>
Signed-off-by: Antoine Pitrou <antoine@python.org>

Author: pitrou

cpp/src/arrow/engine/CMakeLists.txt

@@ -34,7 +34,7 @@ set(ARROW_ENGINE_SRCS
     substrait/relation_internal.cc
     substrait/type_internal.cc)
 
-set(SUBSTRAIT_LOCAL_DIR "${CMAKE_CURRENT_BINARY_DIR}/substrait_clone")
+set(SUBSTRAIT_LOCAL_DIR "${CMAKE_CURRENT_BINARY_DIR}/substrait")
 set(SUBSTRAIT_GEN_DIR "${CMAKE_CURRENT_BINARY_DIR}/generated")
 set(SUBSTRAIT_PROTOS
     capabilities