Remove unintegrated subpackages from beanmachine ShipIt OSS sync (#1713)

Summary:
Pull Request resolved: #1713

RFC; please shamelessly squash if you dislike.

GH Actions CI will fail until D39935525 lands

This diff proposes removing `applications` from our ShipIt export

> To ship an application as a submodule of `beanmachine` Python library, its tests must be integrated with the `beanmachine` library tests under the `beanmachine/tests:test-ppl` buck target.

This arose as we followed up on tests in `applications` https://www.internalfb.com/diff/D39658511?dst_version_fbid=637724844584696&transaction_fbid=1660403447689089.

This is because `applications` packages are all separate fbcode buck build/test targets from `beanmachine/ppl:{test-,}ppl` so colocation of test files under `beanmachine/tests` does not make sense.

As a result: if an application is meant to be shipped as part of the beanmachine library (i.e. moved under `beanmachine/{ppl,graph}` which ShipIt is configured to OSS export), then its corresponding tests __must__ be integrated with the `beanmachine/tests:test-ppl` target in Buck.

Reviewed By: ToddSmall

Differential Revision: D39931700

fbshipit-source-id: aa9f41fbb742debf803bdd4041a1fc2f63077014