[Copilot]

This updates the remaining REST integration tests and matching README snippets to use RestTestClient, replacing deprecated TestRestTemplate usage across the repository. It also ensures each affected module declares the required spring-boot-resttestclient test dependency.

• Scope

  • Migrates the remaining TestRestTemplate / @AutoConfigureTestRestTemplate usages in:
    • data-mongodb-transactional
    • data-domain-events
    • data-rest-validation
    • cloud-jdbc-env-repo
    • test-slice-tests-rest

• Test client migration

  • Replaces injected TestRestTemplate fields with RestTestClient
  • Swaps @AutoConfigureTestRestTemplate for @AutoConfigureRestTestClient
  • Rewrites request flows to the fluent RestTestClient API while keeping existing assertions and scenarios intact:
    • POST requests now use post().uri(...).contentType(...).body(...).exchange()
    • GET requests now use get().uri(...).exchange()
    • DELETE requests now use delete().uri(...).exchange()
    • basic auth now uses request headers via headers(h -> h.setBasicAuth(...))

• Module dependency updates

  • Adds org.springframework.boot:spring-boot-resttestclient to the affected module that did not yet declare it:
    • test-slice-tests-rest/build.gradle.kts

• Documentation alignment

  • Updates the Java snippets in the affected README.adoc files so the documented examples match the migrated test code

Example migration pattern:

restClient.get().uri("/users/{username}", "rashidi.zin")
        .headers(headers -> headers.setBasicAuth("rashidi.zin", "jU$7d3m0pL3a$eRe|ax"))
        .exchange()
        .expectStatus().isOk()
        .expectBody(UserWithoutId.class)
        .returnResult()
        .getResponseBody();