meta: remove building in Docker

.gitlab-ci.yml

@@ -2,10 +2,7 @@ build:
   stage: build
   image: alpine:3.13
   script:
-    - apk add bash abuild
-    - adduser -D ci
-    - addgroup ci abuild
-    - su ci -- "/usr/bin/abuild-keygen" -n -a -i
-    - su ci -- "./build.sh"
+    - echo "$CI_KEY" | ssh-add -
+    - ssh ci@$CI_HOST "cd alpine-root && git pull && ./build.sh"
   rules:
     - if: '$CI_COMMIT_BRANCH == "master"'