OZG-8085 remove unused parts of pipeline

.gitlab-ci.yml

 image: maven:3.9.9-eclipse-temurin-21-alpine
 
 variables:
-  MAVEN_DEPLOY_CLI_OPTS: "--no-transfer-progress -DskipTests"
   MAVEN_CLI_OPTS: >-
     -s .m2/ci_settings.xml --batch-mode
     -Dmaven.plugin.validation=brief
@@ -65,10 +64,6 @@ test-helm:
 .get-version:
   before_script:
     - export PROJECT_VERSION=$(mvn help:evaluate -Dexpression=project.version -q -DforceStdout $MAVEN_CLI_OPTS | cut -d'-' -f1)
-    - export PROJECT_ARTIFACTID=$(mvn help:evaluate -Dexpression=project.artifactId -q -DforceStdout $MAVEN_CLI_OPTS)
-    - export NEXUS_IMAGE_PREFIX="docker.ozg-sh.de/${PROJECT_ARTIFACTID}"
-    - export MERGE_REQUEST_TAG="${PROJECT_VERSION}-MR-${CI_MERGE_REQUEST_IID}"
-    - export SNAPSHOT_TAG="${PROJECT_VERSION}-${CI_COMMIT_BRANCH}"
 
 # Merge request jobs
 push-merge-request-helm-nexus: