6 files declare their use of MemoryStorage in Drupal 10

ExtensionInstallStorageTest.php in core/tests/Drupal/Tests/Core/Config/ExtensionInstallStorageTest.php

ImportStorageTransformerTest.php in core/tests/Drupal/KernelTests/Core/Config/ImportStorageTransformerTest.php

ManagedStorageTest.php in core/tests/Drupal/KernelTests/Core/Config/Storage/ManagedStorageTest.php

MemoryStorageTest.php in core/tests/Drupal/KernelTests/Core/Config/Storage/MemoryStorageTest.php

ReadOnlyStorageTest.php in core/tests/Drupal/Tests/Core/Config/ReadOnlyStorageTest.php

StorageCopyTraitTest.php in core/tests/Drupal/Tests/Core/Config/StorageCopyTraitTest.php