EXISTS fails in case its subquery returns several values

[EmirVildanov]

Bug description

Executing SELECT with EXISTS condition operator fails in case subquery returns several values.

• OS: Linux
• OS Version: Ubuntu 20.04.5 LTS
• Architecture: amd64

Tarantool version: 2.10.5-18-g080d07d71

Steps to reproduce

1. Run tarantool instance
2. Execute box.cfg{}
3. Execute box.execute([[create table t (id integer primary key);]])
4. Execute box.execute([[select * from t where exists (select * from (values (1), (2)));]]) <- on empty table t it runs successfully, returning no rows
5. Execute box.execute([[insert into t values (1);]])
6. Execute box.execute([[select * from t where exists (select * from (values (1), (2)));]]) <- on non-empty table t it fails with error 'Failed to execute SQL statement: Expression subquery returned more than 1 row'

Actual behavior

SELECT from non-empty table with additional EXISTS (which subquery returns two values) condition fails.

Expected behavior

SELECT from non-empty table with additional EXISTS (which subquery returns two values) condition should return all the rows from the table (the result should be the same as if subquery was returning just one value: executing query with values (1) instead of values (1), (2) produce no errors).