refactor(core): remove unused constants (#2872)

Author: iuioiua

src/constants.ts

@@ -1,5 +1,3 @@
 export const INTERNAL_PREFIX = "/_frsh";
-export const DEV_CLIENT_URL = `${INTERNAL_PREFIX}/fresh_dev_client.js`;
 export const DEV_ERROR_OVERLAY_URL = `${INTERNAL_PREFIX}/error_overlay`;
 export const ALIVE_URL = `${INTERNAL_PREFIX}/alive`;
-export const JS_PREFIX = `/js`;