Fix failing test following Tomcat upgrade

Tomcat 8.5.5 has change the default value of `validationInterval` to
3000. See https://bz.apache.org/bugzilla/show_bug.cgi?id=59923 for
details.

See gh-6703
See gh-6657

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/jdbc/TomcatDataSourceConfigurationTests.java

@@ -126,7 +126,7 @@ public class TomcatDataSourceConfigurationTests {
 		assertThat(ds.getTimeBetweenEvictionRunsMillis()).isEqualTo(5000);
 		assertThat(ds.getMinEvictableIdleTimeMillis()).isEqualTo(60000);
 		assertThat(ds.getMaxWait()).isEqualTo(30000);
-		assertThat(ds.getValidationInterval()).isEqualTo(30000L);
+		assertThat(ds.getValidationInterval()).isEqualTo(3000L);
 	}
 
 	@SuppressWarnings("unchecked")