EntityTest Rest tests are misplaced

Problem/Motivation

Rest tests for the EntityTest entity type are placed in core/modules/system/tests/modules/entity_test/tests/src/Functional/Rest. The core/modules/system/tests/modules directory, however, is only supposed to contain test modules not actual tests. Some of those tests are just the generic entity type Rest test coverage for which it is arguable whether it is actually needed for a test entity type. But there are some tests that test the Rest integration of specific entity functionality, so those should definitely be moved.

Steps to reproduce

-

Proposed resolution

Move the tests to...

• ... core/modules/system/tests/src/Functional/Rest?
• ... core/modules/system/tests/src/Functional/Entity?
• ... core/modules/rest/tests/src/Functional?
• ... core/modules/rest/tests/src/Functional/Entity?

Merge request link

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet