Remove process_group_agent and faulty_process_group_agent files (pytorch#62985)

Summary:
Pull Request resolved: pytorch#62985

Remove the process_group_agent and faulty_process_group_agent code now that PROCESS_GROUP backend has been deprecated for RPC (pytorch#55615). Discussed with xush6528 that it was okay to remove ProcessGroupAgentTest and ProcessGroupAgentBench which depended on process_group_agent.

Test Plan: CI tests

Reviewed By: pritamdamania87

Differential Revision: D30195576

fbshipit-source-id: 8b4381cffadb868b19d481198015d0a67b205811

Author: H-Huang

test/cpp/rpc/CMakeLists.txt

@@ -10,7 +10,6 @@ set(TORCH_RPC_TEST_DEPENDENCY_LIBS
 
 if(USE_GLOO)
   list(APPEND TORCH_RPC_TEST_SOURCES
-    ${TORCH_RPC_TEST_DIR}/test_e2e_process_group.cpp
     ${TORCH_RPC_TEST_DIR}/test_e2e_tensorpipe.cpp
   )
 endif()

test/cpp/rpc/test_e2e_process_group.cpp

@@ -371,7 +371,6 @@ libtorch_distributed_extra_sources = [
     "torch/csrc/distributed/rpc/python_call.cpp",
     "torch/csrc/distributed/rpc/python_remote_call.cpp",
     "torch/csrc/distributed/rpc/python_resp.cpp",
-    "torch/csrc/distributed/rpc/process_group_agent.cpp",
     "torch/csrc/distributed/rpc/request_callback.cpp",
     "torch/csrc/distributed/rpc/request_callback_no_python.cpp",
     "torch/csrc/distributed/rpc/rpc_agent.cpp",
@@ -383,7 +382,6 @@ libtorch_distributed_extra_sources = [
     "torch/csrc/distributed/rpc/script_resp.cpp",
     "torch/csrc/distributed/rpc/tensorpipe_agent.cpp",
     "torch/csrc/distributed/rpc/tensorpipe_utils.cpp",
-    "torch/csrc/distributed/rpc/testing/faulty_process_group_agent.cpp",
     "torch/csrc/distributed/rpc/testing/faulty_tensorpipe_agent.cpp",
     "torch/csrc/distributed/rpc/torchscript_functions.cpp",
     "torch/csrc/distributed/rpc/types.cpp",