test(spring-boot): Move the Boot 4 sample's tests into the module

Adds an integrationTest suite to sentry-spring-boot-4 that mirrors the
jakarta one and ports the Boot 4 sample's Person, DistributedTracing,
Todo, Cache, Metrics and GraphQL tests to it. The sample's tests were
copies of the jakarta ones, so the suite is too, adjusted for Spring
Boot 4: Jackson 3, the split restclient and resttestclient modules,
@AutoConfigureTestRestTemplate, and sentry-spring-7's SentrySpan.

The Spring Boot 4 matrix runs the suite against every Boot version it
covers. The sample keeps its Kafka test until the next PR.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Author: runningcode

.github/workflows/spring-boot-4-matrix.yml

@@ -83,6 +83,9 @@ jobs:
             :sentry-samples:sentry-samples-spring-7:testClasses \
             :sentry-opentelemetry:sentry-opentelemetry-agent:assemble
 
+      - name: Test sentry-spring-boot-4 integration suite
+        run: ./gradlew :sentry-spring-boot-4:integrationTest
+
       - name: Run sentry-samples-spring-boot-4
         run: |
           python3 test/system-test-runner.py test \