Precheck is peformed at a global level across all NVDSes present in the
system. It is expected to check the status once the precheck API is
invoked via GetNvdsUpgradeReadinessCheckSummary API. If NVDS configuration
like HostSwitchProfiles differs across TransportNodes, precheck will fail
and status will be FAILED and error will be reported via the
status API. Once the reported errors are fixed, precheck API is expected
to be invoked again to rerun precheck. Once NVDS configuration is
consistent across all TransportNodes, precheck will pass and a topology
will be generated and status will be PENDING_TOPOLOGY. Generated toplogy
can be retrieved via GetRecommendedVdsTopology API. User can apply the
recommended topology via SetTargetVdsTopology API.