Related rails#39039.

Currently PostgreSQL adapter is the only adapter that rely on type
casting by `result.column_types`, now the adapter can return numeric
value without type casting by Active Record side.
So we can remove that useless type cast on aggregated value.

I supposed all aggregation functions will return numeric result in
rails#39039, but that assumption was incorrect for `minimum` and `maximum`,
if an aggregated column is non numeric type.

I've restored type casting aggregated result for `minimum` and `maximum`.

Fixes rails#39110.

This is the opposite direction of rails#39039.

rails#39111 fixes `minimum` and `maximum` on date columns with type casting
by column type on the database. But column type has no information for
time zone aware attributes, it means that attribute type should always
be precedence over column type. I've realized that fact in the related
issue report rails#39248.

I've reverted the expectation of rails#39039, to make time zone aware
attributes works.

…e type

Follow up to rails#39255, rails#39039.

One of the purpose of this was to unify the behavior between the
databases.

Original code was:

```ruby
    type   = result.column_types.fetch(column_alias) do
      type_for(column_name)
    end
```

The code will attempt looking up type from `column_types`, then fallback
to attribute types, so I supposed the code was originally intended to
cast a value by the database types.

But now, most modern clients will already return casted values, and no
longer use `column_types`, except Postgres.
As a result, now most adapter accidentally fallback to attribute types.
Since casted by attribute types sometimes doesn't return numeric values,
I've unified the behavior to use database types consistently in rails#39039.

But later, I've learned that attribute types have important settings
like time zone aware attributes (rails#39255), and some existing code relying
on attribute types over database types (rails#39271).

I've changed all aggregated values are casted by attribute types.

Fixes rails#39271.

To address the issues rails#39248 and rails#39271, rails#39255 and rails#39274 made
aggregated results type casted by the attribute types.

But I've realised that we could avoid enum mapping when implemented
rails#41431.

This change restores the expectation of rails#39039 especially in the Enum
case.

Fixes rails#41600.