AT:

• the variable import for completed process instances is removed
• the variable plugin mechanism still works
• the max page size for variables is adjusted to the new import, which includes adjusting the configurations docs

Context:
Since we are now importing all variable updates, we also have the final result of the variables and there is no need to import the final value of all variables again. Also the variable import for completed process instances is quite complex and does not work as all the other imports work.