Extract spring-boot-test.jar

Relocate the `org.springframework.boot.test` package from the
`spring-boot.jar` to `spring-boot-test.jar`.

Fixes gh-5184

spring-boot-integration-tests/spring-boot-security-tests/spring-boot-security-test-web-helloworld/pom.xml

@@ -31,5 +31,10 @@
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-security</artifactId>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-test</artifactId>
+			<scope>test</scope>
+		</dependency>
 	</dependencies>
 </project>