refactor: improve integration tests stability

- Replace inline StepVerifier assertions with AtomicReference pattern for better testability
- Add assertWith() usage for cleaner assertion blocks in async tests
- Simplify reactive chains using doOnNext() and thenReturn() patterns
- Remove unnecessary Thread.sleep() from elicitation handler
- Improve variable naming (rootsRef → toolsRef) for clarity
- Update timeout error message assertions to be more specific
- Clean up code formatting and remove redundant comments

Signed-off-by: Christian Tzolov <christian.tzolov@broadcom.com>

mcp-spring/mcp-spring-webmvc/src/test/java/io/modelcontextprotocol/server/WebMvcStreamableIntegrationTests.java

@@ -11,8 +11,6 @@ import org.apache.catalina.LifecycleException;
 import org.apache.catalina.LifecycleState;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
-import org.junit.jupiter.params.ParameterizedTest;
-import org.junit.jupiter.params.provider.ValueSource;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.web.reactive.function.client.WebClient;
@@ -29,7 +27,6 @@ import io.modelcontextprotocol.client.transport.WebClientStreamableHttpTransport
 import io.modelcontextprotocol.server.McpServer.AsyncSpecification;
 import io.modelcontextprotocol.server.McpServer.SyncSpecification;
 import io.modelcontextprotocol.server.transport.WebMvcStreamableServerTransportProvider;
-import io.modelcontextprotocol.spec.McpSchema;
 import reactor.core.scheduler.Schedulers;
 
 class WebMvcStreamableIntegrationTests extends AbstractMcpClientServerIntegrationTests {