CodeMod: Replace uses of wangle::IOThreadPoolExecutor
CodeMod: Replace uses of wangle::IOThreadPoolExecutor

Summary: CodeMod: Replace uses of `wangle::IOThreadPoolExecutor` with `folly::IOThreadPoolExecutor`, to which the former is merely an alias.

Reviewed By: andrewjcg

Differential Revision: D6005791

fbshipit-source-id: 75763490f017e5df7c56d4f2a71be99e83edd5be

facebook/bistro,facebook/bistro,facebook/bistro,facebook/bistro,facebook/bistro,facebook/bistro