After removing bulk_gle_passthrough test task, there might be a bunch of code in the shell's bulk_api.js file which can be deleted or simplified now that it no longer has to support legacy reads/writes.

Dave suspects that the entire purpose of the suite was to test that the shell's "bulk API" (https://github.com/mongodb/mongo/blob/0fec5e0d4364d00d30ecb3493c611e9f325bbf9...) works with the legacy op codes.

This is an opportunistic goal.