fa78a2fc67 [tests] Test that nodes respond to getdata with notfound (MarcoFalke)
Pull request description:
If a node has not announced a tx at all, then it should respond to
getdata messages for that tx with notfound, to avoid leaking tx
origination privacy.
In the future this could be adjusted such that a node responds with
notfound when a tx has not been announced to us, but that seems
to be a more involved change. See e.g.
https://github.com/jnewbery/bitcoin/commits/pr14220.1
Tree-SHA512: 6244afa5bd5d8fec9b89dfc02c9958bc370195145a0f3715f33200d6cf73a376c94193d44bf4523867196e6591c53ede8f9b6a77cb296b48c114a117b8c8b1fa
