Regression in iterate on Dicts vs 1.1

[KristofferC]

#31452 introduced a regression in calling iterate on dictionaries as reported by the Nanosoldier run at #31727 (comment).

On master:

julia> d = Dict(3 => 3);

julia> @btime iterate($d);
  106.997 ns (2 allocations: 64 bytes)

With #31452 reverted

julia> @btime iterate($d)
  3.400 ns (0 allocations: 0 bytes)

cc @JeffBezanson, @ndinsmore