ci: remove unused docker configurations from pipeline

Removes unnecessary Docker service and variable configurations from 
the CI pipeline to streamline the build process and reduce complexity.  
This enhances clarity and avoids potential misconfigurations.

.gitlab-ci.yml

@@ -6,15 +6,10 @@ include:
 stages:
 - build
 
-variables:
-  DOCKER_HOST: tcp://docker:2375/
-
 image: buildtool/build-tools:${BUILDTOOLS_VERSION}
 
 build:
   stage: build
-  services:
-  - docker:${DOCKER_DIND_VERSION}
   script:
   - unset BUILDTOOLS_CONTENT
   - build