Currently there are some confusions in net_processing:
- There is confusion between -blocksonly mode and block-relay-only, so adjust all comments to use the same nomenclature.
- Whether to disconnect peers for providing invs/txs is implemented differently. For example, it seems a bit confusing to disconnect block-relay-only peers with relay permission when they send a tx message, but not when they send an inv message. Also, keeping track of their inv announcements seems both wasteful and confusing, as it does nothing. This isn't possible in practice, as outbound connections do not have permissions assigned, but sees fragile to rely on. Especially in light of proposed changes to make that possible: https://github.com/bitcoin/bitcoin/pull/17167
This is a backport of core#25156