Add `nats` build tag from KINE for embedded support #6195

Job	Run time
build / Build	6m 10s
Integration Tests (certrotation)	1m 31s
Integration Tests (etcdrestore)	1m 46s
Integration Tests (localstorage)	1m 29s
Integration Tests (startup)	6m 29s
Integration Tests (custometcdargs)	35s
Integration Tests (etcdsnapshot)	7m 33s
Integration Tests (kubeflags)	6m 38s
Integration Tests (longhorn)	4m 52s
Integration Tests (secretsencryption)	1m 49s
	38m 52s

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