test(bigtable): truncate name of instance to be under 30 chars (#4180)
test(bigtable): truncate name of instance to be under 30 chars (#4180)

* test(bigtable): truncate name of instance to be under 30 chars

* test(bigtable): make sure to compare and print displayname for test error
googleapis/google-cloud-go,googleapis/google-cloud-go,googleapis/google-cloud-go,googleapis/google-cloud-go