Query KV client would benefit from enabling snappy

Triggered by MB-55225 where a RangeScan bug sent a compressed value to the query client.

With Elixir KV assumes that every client enables snappy (although we're not in a position yet to make this mandatory). This lead to some changes in KV document compression where we attempt to keep all documents compressed everywhere, with the assumption that it's rare we'll actually need to compress (as the clients are writing compressed).

The linked MB highlighted that the query client hasn't enabled snappy, so KV is decompressing values (CPU+) and sending uncompressed values (network/memory+), where for elixir overall there is benefit from not doing so.