Change k8s clusterWatcher sendInitialEvents from false to null

[amarvir-dhaliwal]

This should correct an issue where setting sendInitialEvents results in resourceVersion and resourceVersionMatch being expected to be set as well.

[k8s-cluster-watch] ERROR trace_id=c33bfbae149893787aee50dd7157c1a6 span_id=74f6af40bb670d3a misk.clustering.kubernetes.KubernetesClusterWatcher -- connectivity lost to k8s for over 60 seconds; waiting 5000ms before retrying
io.kubernetes.client.openapi.ApiException: Message:
HTTP response code: 422
HTTP response body: {"kind":"Status","apiVersion":"v1","metadata":{},"status":"Failure","message":"ListOptions.meta.k8s.io \"\" is invalid: resourceVersionMatch: Forbidden: sendInitialEvents requires setting resourceVersionMatch to NotOlderThan","reason":"Invalid","details":{"group":"meta.k8s.io","kind":"ListOptions","causes":[{"reason":"FieldValueForbidden","message":"Forbidden: sendInitialEvents requires setting resourceVersionMatch to NotOlderThan","field":"resourceVersionMatch"}]},"code":422}

HTTP response headers: {audit-id=[fa590beb-5754-414d-b480-410861dfaa71], cache-control=[no-cache, private], content-length=[482], content-type=[application/json], date=[Thu, 23 Oct 2025 22:14:37 GMT], x-kubernetes-pf-flowschema-uid=[53ebf2ac-f883-4def-a409-c42ad608573a], x-kubernetes-pf-prioritylevel-uid=[9602a5ff-bf57-4828-a910-b8881d845f09]}
	at io.kubernetes.client.util.Watch.createWatch(Watch.java:107)
	at misk.clustering.kubernetes.KubernetesClusterWatcher.watchCluster(KubernetesClusterWatcher.kt:64)
	at misk.clustering.kubernetes.KubernetesClusterWatcher.startUp$lambda$1(KubernetesClusterWatcher.kt:42)
	at kotlin.concurrent.ThreadsKt$thread$thread$1.run(Thread.kt:30)