Constant mz_persist_client::cfg::STATE_VERSIONS_RECENT_LIVE_DIFFS_LIMIT

pub const STATE_VERSIONS_RECENT_LIVE_DIFFS_LIMIT: Config<usize>;

The # of diffs to initially scan when fetching the latest consensus state, to determine which requests go down the fast vs slow path. Should be large enough to fetch all live diffs in the steady-state, and small enough to query Consensus at high volume. Steady-state usage should accommodate readers that require seqno-holds for reasonable amounts of time, which to start we say is 10s of minutes.

This value ought to be defined in terms of NEED_ROLLUP_THRESHOLD to approximate when we expect rollups to be written and therefore when old states will be truncated by GC.