Restrict Liberty deployment tests to Java 8

OpenLiberty does not yet support Java 9 or 10 and stopping the server
currently hangs when using Java 10.

Closes gh-13141

spring-boot-tests/spring-boot-deployment-tests/spring-boot-deployment-test-wlp/pom.xml

@@ -42,6 +42,12 @@
 			<scope>test</scope>
 		</dependency>
 	</dependencies>
+	<profiles>
+		<profile>
+			<id>jdk8</id>
+			<activation>
+				<jdk>1.8</jdk>
+			</activation>
 			<build>
 				<plugins>
 					<plugin>
@@ -84,4 +90,6 @@
 					</plugin>
 				</plugins>
 			</build>
+		</profile>
+	</profiles>
 </project>