webflux test: use the same exception as other tests (open-telemetry#13400)

Author: laurit

instrumentation/spring/spring-webflux/spring-webflux-5.3/library/src/test/java/io/opentelemetry/instrumentation/spring/webflux/v5_3/SpringWebfluxServerInstrumentationTest.java

@@ -41,7 +41,6 @@ public void stopServer(ConfigurableApplicationContext applicationContext) {
   protected void configure(HttpServerTestOptions options) {
     options.setContextPath(CONTEXT_PATH);
     options.setTestPathParam(true);
-    options.setExpectedException(new RuntimeException(ServerEndpoint.EXCEPTION.getBody()));
 
     options.setExpectedHttpRoute(
         (endpoint, method) -> {

instrumentation/spring/spring-webflux/spring-webflux-5.3/library/src/test/java/io/opentelemetry/instrumentation/spring/webflux/v5_3/TestWebfluxSpringBootApp.java

@@ -97,12 +97,12 @@ Mono<ResponseEntity<String>> error() {
     }
 
     @RequestMapping("/exception")
-    Flux<ResponseEntity<String>> exception() throws Exception {
+    Flux<ResponseEntity<String>> exception() {
       return Flux.just(
           controller(
               EXCEPTION,
               () -> {
-                throw new RuntimeException(EXCEPTION.getBody());
+                throw new IllegalStateException(EXCEPTION.getBody());
               }));
     }