Remove another remnant of the testing magic

cmake/scripts/BuildTests.cmake.in

-MACRO(get_directory_test_target _target _dir)
-  string(REPLACE "@CMAKE_BINARY_DIR@" "" _relative_dir "${_dir}")
-  string(REPLACE "/" "_" ${_target} "${_relative_dir}")
-ENDMACRO(get_directory_test_target _target _dir)
-
-get_directory_test_target(_build_test_target "@CMAKE_CURRENT_BINARY_DIR@")
-execute_process(COMMAND @CMAKE_COMMAND@ --build @CMAKE_BINARY_DIR@ 
-  --target ${_build_test_target})