ci: remove unnecessary docker configuration

Eliminate redundant Docker configurations in the CI setup. This 
streamlines the build process and reduces complexity by removing 
variables and services not needed for the current build 
configuration.

.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:
   - build
   - curl -Os https://uploader.codecov.io/latest/linux/codecov