[Core] put small objects in memory store (#8972)

* remove the put in memory store

* put small objects directly in memory store

* cast data type

* fix another place that uses Put to spill to plasma store

* fix multiple tests related to memory limits

* partially fix test_metrics

* remove not functioning codes

* fix core_worker_test

* refactor put to plasma codes

* add a flag for the new feature

* add flag to more places

* do a warmup round for the plasma store

* lint

* lint again

* fix warmup store

* Update _raylet.pyx

Co-authored-by: Eric Liang <ekhliang@gmail.com>

java/runtime/src/main/resources/ray.default.conf

@@ -102,6 +102,8 @@ ray {
     // See src/ray/ray_config_def.h for options.
     config {
       num_workers_per_process_java: 10
+      // TODO(zhuohan): enable this for java
+      put_small_object_in_memory_store: false
     }
   }