Remove PreApply check in PackagesInstalledWithComposerValidator

Problem/Motivation

In \Drupal\automatic_updates_extensions\Validator\PackagesInstalledWithComposerValidator we add an error if any Drupal Project Composer packages are in stage that aren't in active Composer.

This is because the Update module will only fetch the Update XML for projects that are in the active codebase.

This problem doesn't make Automatic Updates Extensions unusable because you can still update projects as long as they don't add new dependencies that are Drupal projects. But it will be problem that Project Browser has to solve.

Proposed resolution

Once these issue are completed

1. #3307369: Validate all changed or updated Drupal projects with Update XML
2. #3305568: Create a validator that detects duplicate info.yml files in the stage on apply
3. #3305564: Create a validator to stop newly installed packages from overwriting existing directories on apply

It should not matter if newly installed packages were not installed via Composer in PreApply. the above validators will handle that and modules that use Package will not have to check that themselve.

so we can remove the PreApply check in PackagesInstalledWithComposerValidator