Add alpn dependency in integration testing.
Add alpn dependency in integration testing.

ceocoder/cloud-bigtable-client,rameshdharan/cloud-bigtable-client,rameshdharan/cloud-bigtable-client,kevinsi4508/cloud-bigtable-client,agibsonccc/cloud-bigtable-client,googleapis/java-bigtable-hbase,sduskis/cloud-bigtable-client,googleapis/java-bigtable-hbase,derjust/cloud-bigtable-client,waprin/cloud-bigtable-client,kevinsi4508/cloud-bigtable-client,googleapis/java-bigtable-hbase,sduskis/cloud-bigtable-client