reset namespace columns in migration

Merged Jarka Kadlecova requested to merge 3356-fix-migrate into master

What does this MR do?

It tries to fix the broken build

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

Builds are failing due to undefined local variable or method parent_id' for #Namespace:0x00000006bdc8c8` error although this column exists.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

What are the relevant issue numbers?

#3356 (closed)