* Revert "Revert "Move conversion_rate logic from elixir to clickhouse (#3887)"…"

This reverts commit 253fb5d67d300654cd3afc6757f3783c6a3f6514.

* Fix issue with missing columns

The issue came from refactoring event:goal UNION ALL logic and trying to move
name select from first to last. If any other tables were joined, the incorrect
item would be used as an array index, causing this issue.

Added a relevant test.