scale roomid_spacechunk_cache by modifier

Not scaling this was probably unintentional.

src/service.rs

@@ -165,7 +165,16 @@ impl Services {
                 threads: rooms::threads::Service {
                     db,
                 },
-                spaces: rooms::spaces::Service::new(200),
+                spaces: rooms::spaces::Service::new(
+                    #[allow(
+                        clippy::as_conversions,
+                        clippy::cast_sign_loss,
+                        clippy::cast_possible_truncation
+                    )]
+                    {
+                        (200.0 * config.cache_capacity_modifier) as usize
+                    },
+                ),
                 user: db,
             },
             transaction_ids: db,