create separate stage for test builds

.gitlab-ci.yml

 stages:
   - build
+  - build-testimages
   - application-test
 
 consent-provider:
@@ -29,7 +30,7 @@ login-provider:
       - .gitlab-ci.yml
 
 login-provider-mock:
-  stage: build
+  stage: build-testimages
   image:
     name: gcr.io/kaniko-project/executor:debug
     entrypoint: [""]
@@ -42,7 +43,7 @@ login-provider-mock:
       - .gitlab-ci.yml
 
 login-provider-test:
-  stage: build
+  stage: build-testimages
   image:
     name: gcr.io/kaniko-project/executor:debug
     entrypoint: [""]