Allow duplicate "combine column" columns in chill mode (#42314)

* Add suffix to name if column already exists

* Add test for duplicate combine columns

* Use direct question in test

Co-authored-by: Kamil Mielnik <kamil@kamilmielnik.com>

* Fix formatting

* Use createQuestion for other tests too

* Fix table references

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Co-authored-by: Kamil Mielnik <kamil@kamilmielnik.com>