Changed the calculation of the Similar Products maximum comparisons limit

Change how to calculate the maximum allowed limit for product comparisons in Similar Products. The maximum limit for product comparisons is now calculated using the number of comparisons between the two specified ProductSetSelectors instead of a fixed limit for each ProductSetSelector.

This ensures a single product can be compared to the whole product catalog even for large product catalogs ranging up to 20,000,000 products.

• [API] Changed the calculation of the maximum allowed limit for product comparisons in the Similar Products API.