Fix reactive cache handling in NetworkPoliciesController#summary

What does this MR do?

Reactive cache flow goes through the background worker which causes arguments to the PacketFlowQuery to be stringified. This causes reactive cache worker to use a different cache key from the one used by the web process, as a result background worker will not re-calc cache. This patch converts PacketFlowQuery to use arguments that will work consistently for both flows. This patch also updates controller to send :accepted on initial caching request to improve frontend polling logic.

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Does this MR meet the acceptance criteria?

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