Fixes cockroachdb#63735.

This commit addresses cockroachdb#63735 by reworking how constant filters are selected when
being applied to lookup joins. findJoinFilterConstants is adjusted to return the
filter that minimizes the number of returned values, instead of returning the
first matching filter that it finds. This affects lookup joins which have constant
filters due to both CHECK constraints and computed column constraints, as we saw
in cockroachdb#63735.

This has an effect on both standard and inverted lookup joins, as the new test
cases demonstrate. For standard lookup joins, a plan which used to look like:
```sql
SELECT * FROM small INNER LOOKUP JOIN t63735 ON n = y WHERE m = 5 AND n = 15
----
inner-join (lookup t63735)
 ├── flags: force lookup join (into right side)
 ├── lookup columns are key
 ├── inner-join (cross)
 │    ├── values
 │    │    ├── (10,)
 │    │    ├── (20,)
 │    │    └── (30,)
 │    ├── select
 │    │    ├── scan small
 │    │    └── filters
 │    │         ├── n = 15
 │    │         └── m = 5
 │    └── filters (true)
 └── filters
      └── y = 15
```
now looks like:
```sql
inner-join (lookup t63735)
 ├── flags: force lookup join (into right side)
 ├── lookup columns are key
 ├── project
 │    ├── select
 │    │    ├── scan small
 │    │    └── filters
 │    │         ├── n = 15
 │    │         └── m = 5
 │    └── projections
 │         └── 30
 └── filters
      └── y = 15
```

For inverted lookup joins, a plan which used to look like:
```sql
SELECT *
FROM t63735_a AS a INNER INVERTED JOIN t63735_b AS b
ON a.k = 15 AND b.j @> a.j AND b.y = a.k
----
inner-join (lookup t63735_b [as=b])
 ├── lookup columns are key
 ├── inner-join (inverted t63735_b@secondary [as=b])
 │    ├── flags: force inverted join (into right side)
 │    ├── inverted-expr
 │    │    └── b.j @> a.j
 │    ├── inner-join (cross)
 │    │    ├── values
 │    │    │    ├── (10,)
 │    │    │    ├── (20,)
 │    │    │    └── (30,)
 │    │    ├── scan t63735_a [as=a]
 │    │    │    └── constraint: /1: [/15 - /15]
 │    │    └── filters (true)
 │    └── filters
 │         └── y = 15
 └── filters
      └── b.j @> a.j
```
now looks like:
```sql
inner-join (lookup t63735_b [as=b])
 ├── lookup columns are key
 ├── inner-join (inverted t63735_b@secondary [as=b])
 │    ├── flags: force inverted join (into right side)
 │    ├── inverted-expr
 │    │    └── b.j @> a.j
 │    ├── project
 │    │    ├── scan t63735_a [as=a]
 │    │    │    └── constraint: /1: [/15 - /15]
 │    │    └── projections
 │    │         └── 30
 │    └── filters
 │         └── y = 15
 └── filters
      └── b.j @> a.j
```

Release note (sql change): Lookup joins on indexes with computed columns
which are also either constrained by CHECK constraints or use an ENUM data
type may now choose a more optimal plan.