Make WebFlux starter locally available to SNI test apps

See gh-26022

spring-boot-tests/spring-boot-integration-tests/spring-boot-sni-tests/build.gradle

@@ -15,6 +15,7 @@ dependencies {
 	app project(path: ":spring-boot-project:spring-boot-starters:spring-boot-starter", configuration: "mavenRepository")
 	app project(path: ":spring-boot-project:spring-boot-starters:spring-boot-starter-actuator", configuration: "mavenRepository")
 	app project(path: ":spring-boot-project:spring-boot-starters:spring-boot-starter-web", configuration: "mavenRepository")
+	app project(path: ":spring-boot-project:spring-boot-starters:spring-boot-starter-webflux", configuration: "mavenRepository")
 	app project(path: ":spring-boot-project:spring-boot-tools:spring-boot-gradle-plugin", configuration: "mavenRepository")
 
 	intTestImplementation(enforcedPlatform(project(":spring-boot-project:spring-boot-parent")))