refac: modify oauth login logic for unique email addresses

backend/apps/webui/models/users.py

@@ -122,16 +122,9 @@ class UsersTable:
         except:
             return None
 
-    def get_user_by_email(
-        self, email: str, oauth_user: bool = False
-    ) -> Optional[UserModel]:
+    def get_user_by_email(self, email: str) -> Optional[UserModel]:
         try:
-            conditions = (
-                (User.email == email, User.oauth_sub.is_null())
-                if not oauth_user
-                else (User.email == email)
-            )
-            user = User.get(*conditions)
+            user = User.get(User.email == email)
             return UserModel(**model_to_dict(user))
         except:
             return None