Improve execution speed of CacheAutoConfigurationTests

As of Hazelcast 3.7, the bootstrap is pretty slow by default due to the
networking discovery. This commit disables both TCP/IP and multicast
discoveries.

spring-boot-samples/spring-boot-sample-cache/src/main/resources/hazelcast.xml

@@ -14,4 +14,11 @@
 		<management-enabled>true</management-enabled>
 	</cache>
 
+	<network>
+		<join>
+			<tcp-ip enabled="false"/>
+			<multicast enabled="false"/>
+		</join>
+	</network>
+
 </hazelcast>