Support multiple columns when converting int types

What does this MR do?

Relates to #326569 (closed), previous MR !58177 (merged)

Update migration helpers used for converting column types from int to bigint, so that multiple columns on the same table can be updated in one pass. This is a requirement for some of our large tables, that have both primary key and foreign key columns of type int that need to be converted.

Since we have already shipped migrations using these to migrate the events and push_event_payloads tables, we have to maintain backwards compatibility in the migration helpers while supporting the new functionality.

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