Clean up rust tests.

The list of required deps for testing is a lot shorter as we no longer
include as many prebuilt libraries and our list of stdlibs is much
shorter. Remove the libraries we no longer need, and add the
non-prebuilt libstd and libtest to the deps generated for every test.

Bug: 153463188
Test: Soong tests pass.
Change-Id: I94f7b514797ab8d6aedb543ea6afdb07611b7293