check if ipv4Addr or ipv6Addr is empty before calling AnnotatePod()

[zachdorame]

What type of PR is this?
bug

Which issue does this PR fix:
#2687

What does this PR do / Why do we need it:
This PR adds logic to call AnnotatePod() only if exactly one of ipv4Addr or ipv6Addr is non-null.

If an issue # is not available please add repro steps and logs from IPAMD/CNI showing the issue:
N/A

Testing done on this change:

I observe the following log from ipamd.log

{"level":"error","ts":"2023-12-04T17:30:00.883Z","caller":"datastore/data_store.go:607","msg":"DataStore has no available IP/Prefix addresses"}
{"level":"info","ts":"2023-12-04T17:30:00.883Z","caller":"rpc/rpc.pb.go:713","msg":"Send AddNetworkReply: IPv4Addr , IPv6Addr: , DeviceNumber: -1, err: assignPodIPv4AddressUnsafe: no available IP/Prefix addresses"}

which indicates that err is no longer being overwritten.
Also, after running sudo cat plugin.log | grep "Failed SetupPodNetwork" I did not observe a netlink error

Ran make docker-unit-tests, passes unit tests

Will this PR introduce any new dependencies?:

No

Will this break upgrades or downgrades? Has updating a running cluster been tested?:
No, Yes

Does this change require updates to the CNI daemonset config files to work?:

No

Does this PR introduce any user-facing change?:

No

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[jayanthvn]

lgtm

[jdn5126]

@zachdorame since the approach changed, can you update the PR title and description?

[zachdorame]

@zachdorame since the approach changed, can you update the PR title and description?

Updated to reflect new approach