Check empty string in ProductController::assignAttributesCombinations()

[the-ge]

Questions	Answers
Branch?	develop / 8.1.x
Description?	Added a condition to skip the string processing for empty strings. Tested it on a 8.1.2 website, where I have products with 5k combinations from 4 attributes, making the ProductController::assignAttributesCombinations() method return an array with 20k elements. This optimization decreased the time needed by this method from 1.8 - 2.1 seconds to 1.4 - 1.6 seconds on my machine (Docker containers with PHP 8.1 on Manjaro Linux/i3-4170/16GB).
Type?	improvement
Category?	CO
BC breaks?	no
Deprecations?	no
How to test?	Profile the product page for a product with lots of combinations, before and after the change.
UI Tests	https://github.com/the-ge/ga.tests.ui.pr/actions/runs/8851875393
Fixed issue or discussion?	Fixes #36004
Related PRs	---
Sponsor company	Tenita Gabriel PFA

[Hlavtox]

How there could be an empty string in the first place? Attribute value cannot be empty. 🤔

[the-ge]

How there could be an empty string in the first place? Attribute value cannot be empty. 🤔

The subarrays do not contain only attribute values:

    [0] => Array
        (
            [id_attribute] => 1
            [id_attribute_group] => 1
            [attribute] => 25kg
            [group] => Ambalare
            [reference] => OP751VG0/N0100-25
            [ean13] => 
            [isbn] => 
            [upc] => 
            [mpn] => 

Anyway, meanwhile I found this is v1.6 legacy code, so this pull request should probably wait for #36056.

[the-ge]

My bad, I falsely presumed that Github's "Sync fork" could be used to refresh the fork containing the pull request, so now this PR appears to be botched. Sorry, not a Git expert by far.
Can it be salvaged or should I close it and make another one?