[FLINK-5640] [build] Configure the explicit Unit Test file suffix

This closes apache#3211

pom.xml

@@ -965,6 +965,8 @@ under the License.
  <compilerArgument>-Xlint:all</compilerArgument>
  </configuration>
  </plugin>
+
+ <!--surefire for unit tests and integration tests-->
  <plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-surefire-plugin</artifactId>
@@ -980,19 +982,24 @@ under the License.
  <argLine>-Xms256m -Xmx800m -Dmvn.forkNumber=${surefire.forkNumber} -XX:-UseGCOverheadLimit</argLine>
  </configuration>
  <executions>
+ <!--execute all the unit tests-->
  <execution>
  <id>default-test</id>
  <phase>test</phase>
  <goals>
  <goal>test</goal>
  </goals>
  <configuration>
+ <includes>
+ <include>**/*Test.*</include>
+ </includes>
  <excludes>
  <exclude>**/*ITCase.*</exclude>
  <exclude>${flink-fast-tests-pattern}</exclude>
  </excludes>
  </configuration>
  </execution>
+ <!--execute all the integration tests-->
  <execution>
  <id>integration-tests</id>
  <phase>integration-test</phase>