cos_gpu_driver_builder: minor fix for failure case of output url
parsing

Additionally, adds some logging for the build and the upload process.

TEST=manual
invoked sudo docker run
gcr.io/rnv-dev-301509/cos-gpu-driver-builder:latest -alsologtostderr
-config-dir=gs://rnv-nvidia/build/2023-03-27T15:10:41-e09aaa98/ with the
following config:

```
kernel_src_tarball_gcs: "gs://cos-tools/16108.798.21/kernel-src.tar.gz"
kernel_headers_tarball_gcs:
"gs://cos-tools/16108.798.21/kernel-headers.tgz"
nvidia_runfile_address:
"https://us.download.nvidia.com/tesla/510.108.03/NVIDIA-Linux-x86_64-510.108.03.run"
toolchain_tarball_gcs: "gs://cos-tools/16108.798.21/toolchain.tar.xz"
toolchain_env_gcs: "gs://cos-tools/16108.798.21/toolchain_env"
driver_output_gcs_dir:
"gs://rnv-nvidia/nvidia-cos-project/16108.798.21/2"
```

Change-Id: Ifc47c198bda8931a21458f785114088e26dd2f82
Reviewed-on: https://cos-review.googlesource.com/c/cos/tools/+/46189
Tested-by: Arnav Kansal <rnv@google.com>
Cloud-Build: GCB Service account <228075978874@cloudbuild.gserviceaccount.com>
Reviewed-by: Meena Shanmugam <meenashanmugam@google.com>
diff --git a/src/cmd/cos_gpu_driver_builder/internal/config/configs.go b/src/cmd/cos_gpu_driver_builder/internal/config/configs.go
index 80f7567..c8da6e9 100644
--- a/src/cmd/cos_gpu_driver_builder/internal/config/configs.go
+++ b/src/cmd/cos_gpu_driver_builder/internal/config/configs.go
@@ -23,6 +23,7 @@
 	for _, config := range configs {
 		log.Printf("building precompiled GPU driver for %s:%s, driver version %s\n", config.VersionType, config.Version, config.DriverVersion)
 		if processed, _ := gcs.GCSObjectExists(ctx, client, outputDriverFile(config)); processed {
+			log.Println("precompiled driver exists, skipping the build.")
 			continue
 		}
 		dir, precompiledDriver, err := builder.BuildPrecompiledDriver(ctx, client, config)
@@ -34,6 +35,7 @@
 		outputURL, err := url.Parse(config.ProtoConfig.GetDriverOutputGcsDir())
 		if err != nil {
 			log.Printf("failed to parse driver output gcs dir: %v\n", err)
+			continue
 		}
 		outputURL.Path = filepath.Join(outputURL.Path, precompiledDriver)
 		outputDriverFile := outputURL.String()
@@ -43,6 +45,7 @@
 				log.Printf("export failed for: %s, driver version %s: %v\n", config.Version, config.DriverVersion, err)
 				continue
 			}
+			log.Printf("successfully uploaded precompiled GPU driver for %s:%s, driver version %s\n", config.VersionType, config.Version, config.DriverVersion)
 		}
 	}
 	return nil