When switch state replay file is provided, just use the passed in config

Summary:
The idea behind this test is to get to the same state
as was on the switch we pulled the state (and config) from.
So use the passed in config and not the onePortPerInterfaceConfig

Reviewed By: zechengh09

Differential Revision: D61426941

fbshipit-source-id: a04831f2971ecb5f76971326d6acf09377e7dab8

fboss/agent/test/agent_hw_tests/AgentSwitchStateReplayTest.cpp

@@ -31,6 +31,12 @@ class AgentSwitchStateReplayTest : public AgentHwTest {
  public:
   cfg::SwitchConfig initialConfig(
       const AgentEnsemble& ensemble) const override {
+    if (FLAGS_replay_switch_state_file.size()) {
+      // Config must be from the same switch that switch
+      // state was pulled from.
+      return *AgentConfig::fromDefaultFile()->thrift.sw();
+      ;
+    }
     return utility::onePortPerInterfaceConfig(
         ensemble.getSw(), ensemble.masterLogicalPortIds());
   }