hcp: wrap completeBuild to mark as failed on error

When a build cannot be completed without errors, the build state was
left as running, unless the build explicitly failed, which meant that
HCP Packer would be responsible for changing the status after the
heartbeats for the build stopped being sent for two 5m periods.

This commit changes this behaviour, by explicitly marking the build as
failed if something did not work while trying to complete a build on HCP
Packer, even if the local Packer core build succeeded before that.

internal/hcp/registry/types.bucket.go

@@ -642,7 +642,6 @@ func (bucket *Bucket) completeBuild(
 	doneCh, ok := bucket.RunningBuilds[buildName]
 	if !ok {
 		log.Print("[ERROR] done build does not have an entry in the heartbeat table, state will be inconsistent.")
-
 	} else {
 		log.Printf("[TRACE] signal stopping heartbeats")
 		// Stop heartbeating
@@ -662,6 +661,23 @@ func (bucket *Bucket) completeBuild(
 		return packerSDKArtifacts, fmt.Errorf("build failed, not uploading artifacts")
 	}
 
+	artifacts, err := bucket.doCompleteBuild(ctx, buildName, packerSDKArtifacts, buildErr)
+	if err != nil {
+		err := bucket.UpdateBuildStatus(ctx, buildName, hcpPackerModels.HashicorpCloudPacker20230101BuildStatusBUILDFAILED)
+		if err != nil {
+			log.Printf("[ERROR] failed to update build %q status to FAILED: %s", buildName, err)
+		}
+	}
+
+	return artifacts, err
+}
+
+func (bucket *Bucket) doCompleteBuild(
+	ctx context.Context,
+	buildName string,
+	packerSDKArtifacts []packerSDK.Artifact,
+	buildErr error,
+) ([]packerSDK.Artifact, error) {
 	for _, art := range packerSDKArtifacts {
 		var sdkImages []packerSDKRegistry.Image
 		decoder, err := mapstructure.NewDecoder(&mapstructure.DecoderConfig{