Resolve "Improve pipeline speed"

Description

Related Issue

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

Closes #126 (closed)

build/ci/.test.yml

 .integration-test: &integration-test
-  image: golang:1.16
+  image: registry.code.fbi.h-da.de/cocsn/gosdn:testing_${CI_PIPELINE_ID}
   stage: integration-test
   needs:
     - job: "containerlab:deploy"
@@ -34,7 +34,7 @@ integration-test:api:
     - go test -race -v -run TestApiIntegration
 
 .test: &test
-  image: golang:1.16
+  image: registry.code.fbi.h-da.de/cocsn/gosdn:testing_${CI_PIPELINE_ID}
   stage: test
   allow_failure: true
   variables:
@@ -55,6 +55,7 @@ unit-test:
   <<: *test
 
 controller-test:
+  image: golang:1.16
   script:
     - go test -race -v -run TestRun
   <<: *test