Optimize tests with simpler workflow

Signed-off-by: Vasek - Tom C <tom.chauveau@epitech.eu>

pkg/universe.dagger.io/docker/test/build-simple.cue

@@ -4,21 +4,18 @@ import (
 	"dagger.io/dagger"
 	"dagger.io/dagger/engine"
 	"universe.dagger.io/docker"
+	"universe.dagger.io/alpine"
 )
 
 // This test verify that we can correctly build a simplistic image
 // using  docker.#Build
 dagger.#Plan & {
-	#alpineImage: "index.docker.io/alpine:3.15.0@sha256:21a3deaa0d32a8057914f36584b5288d2e5ecc984380bc0118285c70fa8c9300"
-
 	#testValue: "hello world"
 
 	actions: {
 		image: docker.#Build & {
 			steps: [
-				docker.#Pull & {
-					source: #alpineImage
-				},
+				alpine.#Build,
 				docker.#Run & {
 					script: """
 							echo -n $TEST >> /test.txt