Remove partial dependency in PCSContainerService (#1428)

Summary:
Pull Request resolved: #1428

X-link: facebookresearch/fbpcp#405

We decided that validate_container_definitions should not be a public API in container service. This diff is to remove partial dependency in PCSContainerService

The validation logic has been moved in D38629555, to ensure the backward compatibility, we firstly changed the function body to ``pass``.

Differential Revision: D38604420

fbshipit-source-id: fe1f6fb35587ce975f6fce492ec60218facd90fd

fbpcs/common/service/pcs_container_service.py

@@ -7,6 +7,7 @@
 # pyre-strict
 
 from typing import Dict, List, Optional
+from warnings import warn
 
 from fbpcp.entity.container_instance import ContainerInstance
 from fbpcp.error.pcp import PcpError
@@ -81,6 +82,7 @@ def get_current_instances_count(self) -> int:
         return self.inner_container_service.get_current_instances_count()
 
     def validate_container_definition(self, container_definition: str) -> None:
-        return self.inner_container_service.validate_container_definition(
-            container_definition
+        warn(
+            "validate container definitions in container service is deprecated",
+            DeprecationWarning,
         )