Revert "make release also uploads to Hackage"

Since we use the same script for release candidate, which we don't want
to upload to Hackage, remove the automatic upload to Hackage.

The user of make release is supposed to manually run

    cabal upload $(DISTLOC)

after make finishes.

This reverts commit c798644aded3308764a5f1dd19805703b3ebb488.