fix: pom.xml - remove duplicate dependencies / plugin clauses that ca…

…use warnings

This prevents the following errors:

$ mvn install -DskipTests=true
[INFO] Scanning for projects...
[WARNING]
[WARNING] Some problems were encountered while building the effective model for com.google.auth:google-auth-library-oauth2-http:jar:1.20.1-SNAPSHOT
[WARNING] 'dependencies.dependency.(groupId:artifactId:type:classifier)' must be unique: junit:junit:jar -> duplicate declaration of version (?) @ line 249, column 17
[WARNING] 'build.plugins.plugin.(groupId:artifactId)' must be unique but found duplicate declaration of plugin org.apache.maven.plugins:maven-failsafe-plugin @ line 193, column 15
[WARNING]
[WARNING] It is highly recommended to fix these problems because they threaten the stability of your build.
[WARNING]
[WARNING] For this reason, future Maven versions might no longer support building such malformed projects.
[WARNING]

oauth2_http/pom.xml

@@ -169,6 +169,14 @@
             <include>**/functional/*.java</include>
           </includes>
         </configuration>
+        <executions>
+          <execution>
+            <goals>
+              <goal>integration-test</goal>
+              <goal>verify</goal>
+            </goals>
+          </execution>
+        </executions>
       </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
@@ -190,18 +198,6 @@
           </dependency>
         </dependencies>
       </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-failsafe-plugin</artifactId>
-        <executions>
-          <execution>
-            <goals>
-              <goal>integration-test</goal>
-              <goal>verify</goal>
-            </goals>
-          </execution>
-        </executions>
-      </plugin>
     </plugins>
   </build>
 
@@ -246,12 +242,6 @@
       <version>1.3</version>
       <scope>test</scope>
     </dependency>
-    <dependency>
-      <groupId>junit</groupId>
-      <artifactId>junit</artifactId>
-      <version>4.13.2</version>
-      <scope>test</scope>
-    </dependency>
     <dependency>
       <groupId>org.mockito</groupId>
       <artifactId>mockito-core</artifactId>