bug: sds should not self-acknowledge messages

[weboko]

Problem / Description

In the SDS implementation, all messages received are used for acknowledgement purposes.
Including messages that were sent by the local node.

In the context of Waku, one cannot assume their nodes only received messages from other nodes.

Solution

Track messages that were sent by the local node, and discard them for acknowledgement purposes.\

Notes

Long term solution is to introduced a senderId in SDS. This can be tracked another PR for spec and code.
This present solution helps moving the needle to something usable.

[weboko]

Resolved with #2528