hash joins don't work for enums of different types

Setup:
```
"create table animals(e enum('rat','ox','tiger','dog') primary key);",
"create table pets(e enum('cat','dog','fish','rat'));",
"insert into animals values('rat'), ('dog');",
"insert into pets values ('cat'), ('dog'), ('rat');",
```

When testing using `TestSingleScript`, this query returns an empty set, when `{{"rat", "rat"}, {"dog", "dog"}}` is expected.
`select /*+ HASH_JOIN(animals, pets)*/ * from animals join pets on animals.e=pets.e order by animals.e;`

The same query, without the join hint, tested as a `joinOpTest` test also fails when biased for hash joins, which makes sense. What doesn't make sense is that it's able to match the `{"rat", "rat"}` row but not the `{"dog", "dog"}` row.

related to #10316

Reproduce the failure using the TestSingleScript setup and the joinOpTest case mentioned in the issue, forcing the HASH_JOIN hint or hash-join bias. Trace the enum comparison path used by the hash join and compare it with the non-hash join behavior. Done means the query returns both expected pairs, {"rat", "rat"} and {"dog", "dog"}, for enums of different types.

Written by the indexing model from the issue text.