`data_dictionary::database::find_keyspace()` returns a temporary
object, and `data_dictionary::keyspace::user_types()` returns a
references pointing to a member of this temporary object. so we
cannot use the reference after the expression is evaluated. in
this change, we capture the return value of `find_keyspace()` using
universal reference, and keep the return value of `user_types()`
with a reference, to ensure us that we can use it later.
this change silences the warning from GCC-13, like:
```
/home/kefu/dev/scylladb/cql3/statements/authorization_statement.cc:68:21: error: possibly dangling reference to a temporary [-Werror=dangling-reference]
68 | const auto& utm = qp.db().find_keyspace(*keyspace).user_types();
| ^~~
```
Fixes#13725
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closes#13726
108f20c684