Clean pom.xml file #3186 (#3211)

* update as requested
* add meta space size arguments

pom.xml

@@ -99,7 +99,7 @@
         <mockito_version>2.23.4</mockito_version>
         <!-- Build args -->
         <argline>-server -Xms256m -Xmx512m -XX:PermSize=64m -XX:MaxPermSize=128m -Dfile.encoding=UTF-8
-            -Djava.net.preferIPv4Stack=true
+            -Djava.net.preferIPv4Stack=true -XX:MetaspaceSize=64m -XX:MaxMetaspaceSize=128m
         </argline>
         <skip_maven_deploy>false</skip_maven_deploy>
         <updateReleaseInfo>true</updateReleaseInfo>
@@ -195,17 +195,6 @@
     </dependencies>
 
     <profiles>
-        <profile>
-            <id>java6</id>
-            <properties>
-                <maven_jar_version>3.0.2</maven_jar_version>
-                <maven_surefire_version>2.22.1</maven_surefire_version>
-                <maven_deploy_version>2.7</maven_deploy_version>
-                <maven_compiler_version>3.1</maven_compiler_version>
-                <maven_source_version>3.0.1</maven_source_version>
-                <maven_javadoc_version>2.10.1</maven_javadoc_version>
-            </properties>
-        </profile>
         <profile>
             <id>test</id>
             <activation>
@@ -217,33 +206,6 @@
                 <module>dubbo-test</module>
             </modules>
         </profile>
-        <profile>
-            <id>hudson</id>
-            <build>
-                <plugins>
-                    <plugin>
-                        <groupId>org.apache.maven.plugins</groupId>
-                        <artifactId>maven-surefire-plugin</artifactId>
-                        <configuration>
-                            <testFailureIgnore>true</testFailureIgnore>
-                        </configuration>
-                    </plugin>
-                </plugins>
-            </build>
-        </profile>
-        <profile>
-            <id>java8-vm-args</id>
-            <activation>
-                <jdk>[1.8,)</jdk>
-            </activation>
-            <properties>
-                <!-- Build args -->
-                <!-- if you run dubbo on java8+,please use these vm args -->
-                <argline>-server -Xms256m -Xmx512m -XX:MetaspaceSize=64m -XX:MaxMetaspaceSize=128m -Dfile.encoding=UTF-8
-                    -Djava.net.preferIPv4Stack=true
-                </argline>
-            </properties>
-        </profile>
         <profile>
             <id>checkstyle</id>
             <activation>