Simplify and fix cmake frontend build (arangodb#20451)

* Simplify and fix cmake frontend build

The output dependency did not work as intended, because the existence of the build folder alone was already enough for make to conclude that there was nothing to do.

* Fix

Author: mpoeter

cmake/frontend/aardvark.cmake

@@ -5,21 +5,16 @@
 find_package(Nodejs 16 REQUIRED)
 find_package(Yarn REQUIRED)
 
-set(FRONTEND_DESTINATION ${PROJECT_SOURCE_DIR}/js/apps/system/_admin/aardvark/APP/react/build)
+set(FRONTEND_DESTINATION ${PROJECT_SOURCE_DIR}/js/apps/system/_admin/aardvark/APP/react)
 
 add_custom_target(frontend ALL
-  DEPENDS ${FRONTEND_DESTINATION}
-)
-
-add_custom_command(
   COMMENT "create frontend build"
-  OUTPUT ${PROJECT_SOURCE_DIR}/js/apps/system/_admin/aardvark/APP/react/build
-  WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}/js/apps/system/_admin/aardvark/APP/react
+  WORKING_DIRECTORY ${FRONTEND_DESTINATION}
   COMMAND yarn install
   COMMAND yarn build
 )
 
 add_custom_target(frontend_clean
-  COMMAND ${CMAKE_COMMAND} -E remove_directory ${FRONTEND_DESTINATION}
+  COMMAND ${CMAKE_COMMAND} -E remove_directory ${FRONTEND_DESTINATION}/build
   COMMENT "Removing frontend artefacts"
   )