Remove STG dump from ticky_ghc flavour

Dumping STG when building the ticky flavour makes the build take a significantly longer time so I always disable them locally.

If I need the STG for a particular module after doing a ticky profile, I just add -ddump-stg to the top of the file I want to look at in more detail.

Therefore I propose to remove these dumps by default to make my life a bit easier.