Warning due to duplicate MockResolver extensions

[wilkinsona]

[WARNING] Found duplicate and different resources in [org.springframework.boot:spring-boot-test:3.4.0-20241031.110032-485, org.springframework:spring-test:6.2.0-RC3]:   mockito-extensions/org.mockito.plugins.MockResolver

Following spring-projects/spring-framework@d8a6423, we should remove Boot's custom MockResolver and rely on Framework's instead.

[philwebb]

Closing in favor of PR #42988. Thanks @nosan!