fix(backend): Fix issue with FAPI suffixed cookies disabled

For production instances that use the latest ClerkJS and backend
SDKs if the FAPI suffixed cookies are disabled, in every page
refresh a handshake is triggered.
To fix this we should use the un-suffixed cookies when the suffixed
session exists but the suffixed client_uat does not exist.

packages/backend/src/tokens/authenticateContext.ts

@@ -213,6 +213,14 @@ class AuthenticateContext {
       }
     }
 
+    // In case of incorrectly setup suffixed cookies (session exists but client_uat missing)
+    // let's use the un-suffixed cookies to keep the existing behavior.
+    // This case can be reproduced for production instances when new ClerkJS and backend SDK
+    // are used but the FF in FAPI is disabled
+    if (!suffixedClientUat && suffixedSession) {
+      return false;
+    }
+
     return true;
   }