Apple: Remove HDF5 support

[dgovil]

Description of Change(s)

This PR consists of two commits. One that removes HDF5 support from the build_usd.py, and the other that removes it from the USD codebase as a whole.

I split it into two commits so it may ease the ability to pick the level of support you want to leave in. However, I would perhaps suggest removing HDF5 altogether if nobody has objections, as I worry the code will just eventually bit rot, if it hasn't already.

Fixes Issue(s)

• https://github.com/PixarAnimationStudios/OpenUSD/issues/3156

• [X] I have verified that all unit tests pass with the proposed changes

• [X] I have submitted a signed Contributor License Agreement