opt: do not cross-join input of semi-join

This commit fixes a logical correctness bug caused when
`GenerateLookupJoins` cross-joins the input of a semi-join with a set of
constant values to constrain the prefix columns of the lookup index. The
cross-join is an invalid transformation because it increases the size of
the join's input and can increase the size of the join's output.

We already avoid these cross-joins for left and anti-joins (see #59646).
When addressing those cases, the semi-join case was incorrectly assumed
to be safe.

Fixes #78681

Release note (bug fix): A bug has been fixed which caused the optimizer
to generate invalid query plans which could result in incorrect query
results. The bug, which has been present since version 21.1.0, can
appear if all of the following conditions are true: 1) the query
contains a semi-join, such as queries in the form:
`SELECT * FROM t1 WHERE EXISTS (SELECT * FROM t2 WHERE t1.a = t2.a);`,
2) the inner table has an index containing the equality column, like
`t2.a` in the example query, 3) the index contains one or more
columns that prefix the equality column, and 4) the prefix columns are
`NOT NULL` and are constrained to a set of constant values via a `CHECK`
constraint or an `IN` condition in the filter.