Ladakh800bcls: fixup HwSwitchMatcher exception in AgentNeighborTest

Summary:
Desciption:
AgentNeighborTest* failed with following exception
C++ exception with description "HwSwitchMatcher::switchId api must be called only when there is a single switchId" thrown in the test body.

Root Cause:
On multi NPU platform, in function facebook::fboss::utility::NeighborInfo getNeighborInfo, when calling following
auto switchId = ensemble.getSw()
->getScopeResolver()
->scope(ensemble.masterLogicalPortIds())
.switchId();

scope(ensemble.masterLogicalPortIds()) returns an array, so can't get switchId().

Fix:
As this function is designed to retrieve the current state of neighbor entry for a specific interfaceId directly from the ASIC, so changed to get the switchId based on the interfaceId information.

Reviewed By: daiwei1983

Differential Revision: D90621646

fbshipit-source-id: 1e9f785b2da532c46052c9fe8d1ee607dd791cef

Author: huruinan

fboss/agent/test/agent_hw_tests/AgentNeighborTests.cpp

@@ -36,10 +36,13 @@ facebook::fboss::utility::NeighborInfo getNeighborInfo(
     const facebook::fboss::InterfaceID& interfaceId,
     const folly::IPAddress& ip,
     facebook::fboss::AgentEnsemble& ensemble) {
-  auto switchId = ensemble.getSw()
-                      ->getScopeResolver()
-                      ->scope(ensemble.masterLogicalPortIds())
-                      .switchId();
+  auto state = ensemble.getProgrammedState();
+  auto intf = state->getInterfaces()->getNodeIf(interfaceId);
+  if (!intf) {
+    throw facebook::fboss::FbossError("no such interface ", interfaceId);
+  }
+  auto switchId =
+      ensemble.getSw()->getScopeResolver()->scope(intf, state).switchId();
   auto client = ensemble.getHwAgentTestClient(switchId);
   facebook::fboss::IfAndIP neighbor;
   neighbor.interfaceID() = interfaceId;