Build a public CI for Apache Cassandra Java Driver

Since the driver was donated to ASF, we do not yet have a CI platform to share test results. We need one.

We plan to proceed with two Jenkinsfile, one `Jenkinsfile-asf` for the public ASF-CI, and one `Jenkinsfile-datastax` for DataStax internal tests. `Jenkinsfile-asf` will only run open-source Cassandra integration tests, while the DataStax one will run DSE integration tests.