Suggestion: Update DiscoverSriovDevices to use /sys/class/net in order to support netns isolation

[oshoval]

We found out that there is a case in which the user needs to distribute the PFs exclusivity in a few network namespaces.
For example running two clusters, each with its own netns,
and each netns with one PF exclusivity (assigned by ip link set <PF> netns <NS>).
One use case, for example, is to run 2 prow jobs on the same node, each with its own PF and netns.

Since current config-daemon DiscoverSriovDevices detects the interfaces via /sys/devices/pci*,
all the PFs would be visible because the daemon runs on host netns.
As a result the unconfigured PFs will be reset in resetSriovDevice which is called by SyncNodeState.
This will cause one cluster to corrupt the 2nd cluster, even if the PF isn't in its own netns.

Please consider using /sys/class/net/*/device/uevent for discovering instead.
Tested it for the above scenario and it fixed the problem,
i could run two clusters, each with its own PF, side by side on the same node.

As we spoke, it should be discussed if there are use cases where the daemon still needs to discover all the interfaces, via /sys/devices/pci* and then a flag should be added in order to select the desired discovery method.

see U/S k8snetworkplumbingwg/sriov-network-operator#2

/cc @zshi-redhat

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[oshoval]

Fixed on upstream