Revert "[CMake] Disable linking against shared LLVM also for builtin_clang=OFF"

This reverts commit 3ef1193. The
taken approach is not correct, this should be handled on the linking
side of libCling as discussed post-merge in the pull request:
#18386

Author: hahnjo

interpreter/CMakeLists.txt

@@ -407,12 +407,6 @@ if (builtin_clang)
 else()
   find_package(Clang REQUIRED CONFIG)
   message(STATUS "Found Clang ${CLANG_PACKAGE_VERSION} in ${CLANG_CMAKE_DIR}")
-
-  # Disable linking against shared LLVM.
-  # We have to do this after find_package(Clang). Finding Clang internally
-  # calls find_package(LLVM), which overwrites LLVM_LINK_LLVM_DYLIB to what it
-  # was set when building LLVM.
-  set(LLVM_LINK_LLVM_DYLIB FALSE)
 endif()
 
 # Reset the compiler flags after compiling LLVM and Clang