Blocksy: responsive breakpoints not followed

[bfintal]

The filter for adjusting the responsive breakpoints via stackable_responsive_breakpoints seems to be not working anymore.

Might be related to #3394

Steps to replicate:

1. have this filter in place:

2. Make sure there are no Stackable responsive settings set
3. Check in the frontend, the blocks use max-width: 1023px for tablet and max-width: 767px for mobile

Screen.Capture.on.2025-02-12.at.11-20-12.mp4