CMake: remove non-functioning logic to delete files before installing

This logic has not been working since 2014 [0] although it was briefly
fixed (by accident) when TARGETDIR_VER was made an absolute directory
[1] (since reverted as that caused problems with CPACK/WIN32).

"file(REMOVE_RECURSE ${TARGETDIR_VER})" would attempt to remove:
- "${CMAKE_BINARY_DIR}/${TARGETDIR_VER}" instead of
- "${CMAKE_INSTALL_PREFIX}/${TARGETDIR_VER}".

While this could be re-enabled by correcting the path,
it slows down the install target by copying files every "install".

This could be made to detect changes and only cleaning files in this
case however this ends up being fairly involved, see: PR !111084.

As stale files haven't been causing problems as far as I'm aware,
remove this code.

[0]: e43c5fa005
[1]: d605cc7574

source/creator/CMakeLists.txt

@@ -421,13 +421,6 @@ endif()
 # -----------------------------------------------------------------------------
 # Install Targets (Generic, All Platforms)
 
-
-# Important to make a clean install each time, else old scripts get loaded.
-install(
-  CODE
-  "file(REMOVE_RECURSE ${TARGETDIR_VER})"
-)
-
 if(WITH_PYTHON)
   # install(CODE "message(\"copying blender scripts...\")")