Remove redundant OPTIONS_GHC pragmas from templates

[sol]

There are two things that I lack the context and background to comprehend.

1. For what reason would these pragmas be needed in the first place?
2. What was the rational for changing these in https://github.com/haskell/cabal/commit/f47768ae15e2bfc14ac2a2a43afe85d522c470f0? Was it simply an oversight, or are we at the point where "a subjective urge for tidiness" takes precedences over providing value to the user and backwards compatibility?

• [ ] squash commits (I did this through GitHub UI from mobile..)