Lazily register `DynamicValuesPropertySource` in the TestContext framework

[sbrannen]

Overview

As a result of commit 6cdb344, the DynamicValuesPropertySource is now eagerly registered in the Environment even if the DynamicPropertyRegistry is never used to register dynamic properties.

Ideally, we should only register DynamicValuesPropertySource if we know that the DynamicPropertyRegistry is used -- either by a @DynamicPropertySource method in a test class or via a bean in the ApplicationContext that invokes add() on the DynamicPropertyRegistry bean.

Related Issues

• Register DynamicPropertyRegistry as a singleton bean in a test's ApplicationContext #32271