Convert test annotations to attributes in modules' BuildTests

I ran these commands:
phpunit --list-tests --group package_manager | grep Package
phpunit --list-tests --group="#slow" | grep Package

on both this MR branch and 11.x and confirmed that the following all show up as expected:

 - Drupal\Tests\package_manager\Build\PackageInstallDirectWriteTest::testPackageInstall
 - Drupal\Tests\package_manager\Build\PackageInstallSubmoduleTest::testSubModules
 - Drupal\Tests\package_manager\Build\PackageInstallTest::testPackageInstall
 - Drupal\Tests\package_manager\Build\PackageUpdateTest::testPackageUpdate

Changes look straightforward. LGTM.

catch → closed merge request !12569

Committed/pushed to 11.x, thanks!

Automatically closed - issue fixed for 2 weeks with no activity.