Revert "[ao] Added insertion of observer capability to ModelReport class"
This reverts commit 1cff4147846693b8ded796067755b81ccbc6bc30.
Reverted https://github.com/pytorch/pytorch/pull/79752 on behalf of https://github.com/malfet due to Part of the stack that broke tests on MacOS, see https://hud.pytorch.org/pytorch/pytorch/commit/0f95e1846c1e8da2e0524243bbd6761434e43b5a
