[Clang] Remove redundant init-parens in AST print

Given a dependent `T` (maybe an undeduced `auto`),

Before:

    new T(z)  -->  new T((z))  # changes meaning with more args
    new T{z}  -->  new T{z}
        T(z)  -->      T(z)
        T{z}  -->      T({z})  # forbidden if T is auto

After:

    new T(z)  -->  new T(z)
    new T{z}  -->  new T{z}
        T(z)   -->     T(z)
        T{z}   -->     T{z}

Depends on D113393

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D120608