Revert last canary flag PR and use a better method (#5535)

* Revert "Implement Labrinth Canary API flag (#5531)"

This reverts commit 3b21944a75.

* Use Labrinth-Canary header instead of cookie for API canary

* prepr

* fix rebase

packages/api-client/src/index.ts

@@ -9,11 +9,6 @@ export {
 } from './core/abstract-websocket'
 export { ModrinthApiError, ModrinthServerError } from './core/errors'
 export { type AuthConfig, AuthFeature } from './features/auth'
-export {
-	type CanaryCookieConfig,
-	CanaryCookieFeature,
-	LABRINTH_CANARY_COOKIE,
-} from './features/canary-cookie'
 export {
 	type CircuitBreakerConfig,
 	CircuitBreakerFeature,