use generate_lib to replace generate_lib_all_ops (#2315)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/2315
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`generate_lib` target (https://www.internalfb.com/code/fbsource/[53b009cbd8ee]/fbcode/executorch/kernels/portable/targets.bzl) has covered both aten ops and custom ops, which equals to all ops under portbale lib and make `generate_lib_all_ops` target reduntant. This diff removes `generate_lib_all_ops` and replace all places depending on it with `generate_lib`.

Reviewed By: larryliu0820

Differential Revision: D54671576

fbshipit-source-id: cf524fccc5e794948cd5478b361208814cfaefce