CI: optimize Maven usage

.gitlab-ci.yml

@@ -1,8 +1,6 @@
 build:
   script:
-    - mvn -Dmaven.repo.local=/tmp/m2/repository -Duser.home=/tmp checkstyle:check
-    - mvn -Dmaven.repo.local=/tmp/m2/repository -Duser.home=/tmp test
-    - mvn -Dmaven.repo.local=/tmp/m2/repository -Duser.home=/tmp jacoco:prepare-agent test jacoco:report
+    - mvn -Dmaven.repo.local=/tmp/m2/repository -Duser.home=/tmp checkstyle:check jacoco:prepare-agent test jacoco:report
     - python3 /opt/cover2cover.py target/site/jacoco/jacoco.xml src/main/java > target/site/cobertura.xml
     - python3 /opt/source2filename.py target/site/cobertura.xml
     - /opt/calcCoverage.sh < target/site/cobertura.xml

pom.xml

@@ -209,13 +209,6 @@
                 <groupId>org.jacoco</groupId>
                 <artifactId>jacoco-maven-plugin</artifactId>
                 <version>0.8.6</version>
-                <executions>
-                    <execution>
-                        <goals>
-                            <goal>prepare-agent</goal>
-                        </goals>
-                    </execution>
-                </executions>
             </plugin>
 
             <plugin>
@@ -353,4 +346,4 @@
             </plugin>
         </plugins>
     </reporting>
-</project>
+</project>