Fixed #23758

- intentional breakage with recursion limit
- extents the alphabet ( to use multi letter ) for get alias prefix

executed from `test_subquery_condition` (queries.tests.Queries1Tests)
Are there situations in which this can happen other than "too many subqueries"? If not, I'd suggest an error message that might be more helpful to the end user would be "Maximum recursion depth exceeded: too many subqueries."