fix buildpack output to go through API (#6530)

pkg/skaffold/build/buildpacks/lifecycle.go

@@ -32,7 +32,6 @@ import (
 	"github.com/buildpacks/pack/project"
 
 	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/docker"
-	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/output"
 	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/output/log"
 	latestV1 "github.com/GoogleContainerTools/skaffold/pkg/skaffold/schema/latest/v1"
 )
@@ -97,7 +96,7 @@ func (b *Builder) build(ctx context.Context, out io.Writer, a *latestV1.Artifact
 
 	builderImage, runImage, pullPolicy := resolveDependencyImages(artifact, b.artifacts, a.Dependencies, b.pushImages)
 
-	if err := runPackBuildFunc(ctx, output.GetUnderlyingWriter(out), b.localDocker, pack.BuildOptions{
+	if err := runPackBuildFunc(ctx, out, b.localDocker, pack.BuildOptions{
 		AppPath:         workspace,
 		Builder:         builderImage,
 		RunImage:        runImage,

pkg/skaffold/build/buildpacks/logger.go

@@ -20,10 +20,7 @@ import (
 	"io"
 
 	"github.com/buildpacks/pack/logging"
-	"github.com/mattn/go-colorable"
 	"github.com/sirupsen/logrus"
-
-	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/util"
 )
 
 // logger exists to meet the requirements of the pack logger.
@@ -33,11 +30,6 @@ type logger struct {
 }
 
 func NewLogger(out io.Writer) logging.Logger {
-	// If out is not a terminal, let's make sure no colors are printed.
-	if _, isTerm := util.IsTerminal(out); !isTerm {
-		out = colorable.NewNonColorable(out)
-	}
-
 	l := logrus.New()
 	l.SetOutput(out)