Ambiguous field identifier when parsing unions with unqualified columns and parseWithMetaLookups

[lukaseder]

Given this schema:

create table t1 (a int);
create table t2 (a int);

Parsing this valid SQL:

select a
from t1
union all
select a
from t2

Yields:

Ambiguous field identifier: [2:1] select a
[*]from t1
union all
select a
from t2

---

Related: #10699

[lukaseder]

Not a 3.15 regression, the issue is also present in 3.14.4

[lukaseder]

Fixed in jOOQ 3.15.0 and 3.14.4 (#10969)