inputs.nftables: Use nft --terse to avoid dumping set elements

### Use Case

Dumping sets can be expensive. nft allows avoiding that using `--terse`.

### Expected behavior

* Use `--terse` if `include = [...]` does not include `"sets"`.
* nftables master [now provides set element counts](https://git.netfilter.org/nftables/commit/?id=c429340e41b9b32fda214a7a658ae58bc9bfb3d2), so `"sets"` can be monitored even with `--terse`. An option is provided to do so.

### Actual behavior

Sets are always dumped, even when not needed. For large contended sets this can take minutes to hours(!) for a single invocation.

### Additional info

_No response_

Start by locating the inputs.nftables implementation and its handling of the include option, then inspect the existing plugin tests. Verify the nft invocation uses --terse when sets are excluded, while preserving set monitoring through the provided option; add or update tests for both modes.

Written by the indexing model from the issue text.