feat: configurable tracking image

templates/gitlab-ci-maven.yml

@@ -14,6 +14,9 @@
 # Floor, Boston, MA  02110-1301, USA.
 # =========================================================================================
 variables:
+  # variabilized tracking image
+  TBC_TRACKING_IMAGE: "$CI_REGISTRY/to-be-continuous/tools/tracking:master"
+
   # Default Maven project root directory
   MAVEN_PROJECT_DIR: .
 
@@ -427,7 +430,7 @@ stages:
 .mvn-base:
   image: $MAVEN_IMAGE
   services:
-    - name: "$CI_REGISTRY/to-be-continuous/tools/tracking:master"
+    - name: "$TBC_TRACKING_IMAGE"
       command: ["--service", "maven", "2.2.0" ]
   before_script:
     - *mvn-scripts