[Static Runtime] Move PrepackWeights to internal-only graph passes (#87799)
Summary:
The pass introduces an `fb::` operator and thus cannot be used in OSS.
The test failure was not exposed because the Static Runtime tests have been disabled in OSS for a while. The Dev Infra folks encountered this failure when re-enabling the tests.
Test Plan: Existing tests
Differential Revision: D40724547
Pull Request resolved: https://github.com/pytorch/pytorch/pull/87799
Approved by: https://github.com/huydhn
