bigtable/bttest: Fix fully-qualified column family identifier construction.
bigtable/bttest: Fix fully-qualified column family identifier construction.

Change-Id: Ic253f2e459ca6507fea162b3123bf20e0d9a0c39

googleapis/google-cloud-go,ptomasroos/gcloud-golang,michael-grosshans/google-cloud-go,roth1002/gcloud-golang,hsinhoyeh/gcloud-golang,blowmage/gcloud-golang,blowmage/gcloud-golang,hsinhoyeh/gcloud-golang,googleapis/google-cloud-go,roth1002/gcloud-golang,googleapis/google-cloud-go,ptomasroos/gcloud-golang,Maksadbek/gcloud-golang,Maksadbek/gcloud-golang,googleapis/google-cloud-go,michael-grosshans/google-cloud-go