Support fixed test ports in local alluxio cluster

Many of our tests can fail if a certain port is bound at the wrong time.

1. Test starts a local alluxio cluster on port 0
2. The cluster finds an available port to bind, e.g. 12345
3. The cluster is stopped, unbinding port 12345
4. Another cluster binds port 12345 now that it is available
5. The original test tries to restart its cluster, but it fails now because it can't re-bind port 12345

We've addressed this issue in MultiProcessCluster by enabling tests to coordinate which ports they use so that they won't conflict with other tests. We should be able to do something similar for LocalAlluxioCluster tests that require restart.