fix: Advertise m.forget_forced_upon_leave capability according to config

changelog.d/2452.bugfix.md

@@ -0,0 +1 @@
+The `m.forget_forced_upon_leave` capability now reflects the `forget_forced_upon_leave` config option instead of always being advertised as enabled.

src/api/client/capabilities.rs

@@ -46,7 +46,8 @@ pub(crate) async fn get_capabilities_route(
 	capabilities.get_login_token =
 		GetLoginTokenCapability::new(services.server.config.login_via_existing_session);
 
-	capabilities.forget_forced_upon_leave.enabled = true;
+	capabilities.forget_forced_upon_leave.enabled =
+		services.server.config.forget_forced_upon_leave;
 
 	if services.users.is_admin(sender_user).await {
 		capabilities.account_moderation.lock = true;