Expose order values of `TestExecutionListener` implementations as constants

[sbrannen]

Overview

The order values of TestExecutionListener implementations (such as the DependencyInjectionTestExecutionListener) are currently hard-coded in their getOrder() methods.

However, it would be beneficial to users and integrators if those values were exposed as constants (see #34225 (comment)).

Related Issues

• DirtiesContextTestExecutionListener has unexpected execution order leading to errors #34225
• Document order values for TestExecutionListener implementations #34265

Deliverables

• Introduce ORDER constant in each standard TestExecutionListener implementation in spring-test.