bigtable: fix erroneous package name
bigtable: fix erroneous package name

From https://code-review.googlesource.com/23711.

Change-Id: I9a66f36b7f6515d2814fd3161d27afc57a799eb1
Reviewed-on: https://code-review.googlesource.com/24451
Reviewed-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Reviewed-by: Chris Broadfoot <0c2851a4f8ab4aa5606e69c0757771dd13dbe686@google.com>

googleapis/google-cloud-go,googleapis/google-cloud-go,googleapis/google-cloud-go,googleapis/google-cloud-go