[BCID] Don't run builds in parallel in build-images

This doesn't error out, but it doesn't work as intended due to a lock.

Change-Id: I80a2ca77d0948abda97c0e2889521a3968926183
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/584181
Reviewed-by: Ravi Mistry <rmistry@google.com>
Commit-Queue: Ravi Mistry <rmistry@google.com>
Commit-Queue: Eric Boren <borenet@google.com>
Auto-Submit: Eric Boren <borenet@google.com>
diff --git a/cd/go/build-images/BUILD.bazel b/cd/go/build-images/BUILD.bazel
index bb94c2b..18bbee8 100644
--- a/cd/go/build-images/BUILD.bazel
+++ b/cd/go/build-images/BUILD.bazel
@@ -20,7 +20,6 @@
         "//task_driver/go/lib/git_steps",
         "//task_driver/go/td",
         "@com_github_urfave_cli_v2//:cli",
-        "@org_golang_x_sync//errgroup",
     ],
 )
 
diff --git a/cd/go/build-images/build.go b/cd/go/build-images/build.go
index d429f99..e72d6d9 100644
--- a/cd/go/build-images/build.go
+++ b/cd/go/build-images/build.go
@@ -12,7 +12,6 @@
 	"go.skia.org/infra/go/skerr"
 	"go.skia.org/infra/task_driver/go/lib/git_steps"
 	"go.skia.org/infra/task_driver/go/td"
-	"golang.org/x/sync/errgroup"
 )
 
 func build(ctx context.Context, commit, repo, workspace, username, email string, targets []string, rbe bool) error {
@@ -53,7 +52,6 @@
 	imageInfo := &buildImagesJSON{
 		Images: make([]*SingleImageInfo, 0, len(bazelTargetToImagePath)),
 	}
-	eg, ctx := errgroup.WithContext(ctx)
 	for bazelTarget, imagePath := range bazelTargetToImagePath {
 		// https://golang.org/doc/faq#closures_and_goroutines
 		bazelTarget := bazelTarget
@@ -62,12 +60,9 @@
 			Image: imagePath,
 			Tag:   imageTag,
 		})
-		eg.Go(func() error {
-			return bazelRun(ctx, checkoutDir, bazelTarget, louhiImageTag, rbe)
-		})
-	}
-	if err := eg.Wait(); err != nil {
-		return td.FailStep(ctx, err)
+		if err := bazelRun(ctx, checkoutDir, bazelTarget, louhiImageTag, rbe); err != nil {
+			return td.FailStep(ctx, err)
+		}
 	}
 	return writeBuildImagesJSON(ctx, workspace, imageInfo)
 }