Remove reference to spring.datasource.jmx-enabled

This commits moves the single use of that property to the already
existing Tomcat-specific one.

Closes gh-16673

spring-boot-samples/spring-boot-sample-data-jpa/src/test/java/sample/data/jpa/SampleDataJpaApplicationTests.java

@@ -42,8 +42,7 @@ import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.
  * @author Dave Syer
  */
 // Enable JMX so we can test the MBeans (you can't do this in a properties file)
-@SpringBootTest(
-		properties = { "spring.jmx.enabled:true", "spring.datasource.jmx-enabled:true" })
+@SpringBootTest(properties = "spring.jmx.enabled:true")
 @ActiveProfiles("scratch")
 // Separate profile for web tests to avoid clashing databases
 class SampleDataJpaApplicationTests {