Refactor validate for GitHub Actions

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

hack/lint

@@ -1,37 +1,6 @@
 #!/usr/bin/env bash
 
 . $(dirname $0)/util
-set -eu -o pipefail -x
+set -eu
 
-: ${CONTINUOUS_INTEGRATION=}
-
-progressFlag=""
-if [ "$CONTINUOUS_INTEGRATION" == "true" ]; then progressFlag="--progress=plain"; fi
-
-lintDocker() {
-  export DOCKER_BUILDKIT=1
-  iidfile=$(mktemp -t docker-iidfile.XXXXXXXXXX)
-  docker build --iidfile $iidfile -f ./hack/dockerfiles/lint.Dockerfile --force-rm .
-  iid=$(cat $iidfile)
-  docker rmi $iid
-  rm -f $iidfile
-}
-
-lint() {
-  buildctl build $progressFlag --frontend=dockerfile.v0 \
-    --local context=. --local dockerfile=. \
-    --frontend-opt filename=./hack/dockerfiles/lint.Dockerfile
-}
-
-case $buildmode in
-"buildkit")
-  lint
-  ;;
-"docker-buildkit")
-  lintDocker
-  ;;
-*)
-	echo "buildctl or docker with buildkit support is required"
-  exit 1
-  ;;
-esac
+buildxCmd build --file ./hack/dockerfiles/lint.Dockerfile .