[LLVM] Remove `prepare-check-lit` from lit testsuite dependencies (#159922)
Remove `prepare-check-lit` as it's not intended to prepare the
`llvm-lit` binary (which was the original intent of adding this target
to the dependencies). `llvm-lit` is pre-populated when you run cmake, so
there is no need to have an extra dependency for that. That also means
that if you do `rm -rf build/bin` and then run `ninja -C build
check-llvm-filecheck` llvm-lit will not get copied over and you need to
run cmake again to get it back.