Remove updatable-bcp-packages.txt.

Historically, this file was used by the `--updatable-bcp-packages-file`
flag for dex2oat. The flag is no longer needed and is being deprecated.

Unfortunately, we cannot remove `permitted_packages` and all the code
related to it because we still need it for checking the module
compatibility with Q and R.

Bug: 200241946
Test: m nothing
Change-Id: Ie3be54fd47a847ba0caf627d12da76b415d99466