kokoro: fixes build.sh script
kokoro: fixes build.sh script

Change-Id: I61e8aa23b6997492fa1a73d4fcdf85eeeb474cb6
Reviewed-on: https://code-review.googlesource.com/10272
Reviewed-by: Chris Broadfoot <0c2851a4f8ab4aa5606e69c0757771dd13dbe686@google.com>

michael-grosshans/google-cloud-go,michael-grosshans/google-cloud-go