Remove legacy Ray code. (#3121)

* Remove legacy Ray code.

* Fix cmake and simplify monitor.

* Fix linting

* Updates

* Fix

* Implement some methods.

* Remove more plasma manager references.

* Fix

* Linting

* Fix

* Fix

* Make sure class IDs are strings.

* Some path fixes

* Fix

* Path fixes and update arrow

* Fixes.

* linting

* Fixes

* Java fixes

* Some java fixes

* TaskLanguage -> Language

* Minor

* Fix python test and remove unused method signature.

* Fix java tests

* Fix jenkins tests

* Remove commented out code.

test/multi_node_test.py

@@ -201,9 +201,6 @@ def ray_start_head_with_resources():
     subprocess.Popen(["ray", "stop"]).wait()
 
 
-@pytest.mark.skipif(
-    os.environ.get("RAY_USE_XRAY") == "0",
-    reason="This test only works with xray.")
 def test_drivers_release_resources(ray_start_head_with_resources):
     redis_address = ray_start_head_with_resources