Chore: update deprecated sonarqube properties and add properties needed for MR decoration.

Update all deprecated SonarQube properties and force the jacoco XML report file generation in order to get backend code coverage statistics.
Add properties needed for MR decoration.
See GNP-6039 and GNP-5961.

.gitlab-ci.yml

@@ -62,10 +62,16 @@ test-and-sonarqube:
       command: ["bin/elasticsearch", "-Ediscovery.type=single-node"]
   variables:
     GRADLE_OPTS: "-Dorg.gradle.daemon=true"
+    SONAR_USER_HOME: "${CI_PROJECT_DIR}/.sonar"  # Defines the location of the analysis task cache
+    GIT_DEPTH: "0"  # Tells git to fetch all the branches of the project, required by the analysis task
     SONAR_BRANCH_OPTS: "-Dsonar.pullrequest.key=$CI_MERGE_REQUEST_ID -Dsonar.pullrequest.branch=$CI_COMMIT_REF_NAME"
+  cache:
+    key: "${CI_JOB_NAME}"
+    paths:
+      - .sonar/cache
   script:
     - ./gradlew :frontend:test --parallel
-    - ./gradlew :backend:test --parallel
+    - ./gradlew :backend:test jacocoTestReport --parallel
     - find /tmp/node/*/bin -name node -exec ln -s {} /tmp/node/node \;
     - export PATH="/tmp/node/:$PATH"
     - ./gradlew -s sonarqube -x test $SONAR_BRANCH_OPTS