Remove test package in pushgateway and redundant test

Signed-off-by: huan.huynh <[email protected]>

Author: hmhuan

prometheus-metrics-exporter-pushgateway/pom.xml

@@ -39,11 +39,5 @@
       <version>${project.version}</version>
       <scope>test</scope>
     </dependency>
-    <dependency>
-      <groupId>com.squareup.okhttp3</groupId>
-      <artifactId>mockwebserver</artifactId>
-      <version>5.3.0</version>
-      <scope>test</scope>
-    </dependency>
   </dependencies>
 </project>