perf: disable readahead on slot-preimage MDBX environment (#23183)

Co-authored-by: joshieDo <93316087+joshieDo@users.noreply.github.com>

crates/stages/stages/src/stages/execution/slot_preimages.rs

@@ -48,6 +48,7 @@ impl SlotPreimages {
         builder.write_map();
         builder.set_flags(EnvironmentFlags {
             no_sub_dir: false,
+            no_rdahead: true,
             mode: Mode::ReadWrite { sync_mode: SyncMode::Durable },
             ..Default::default()
         });