chore: Remove Filters column from the Product List blocks

Remove Bootstrap Hardcoding

Example change:

// Before
'#item_attributes' => ['class' => ['col-12', 'col-md-6', 'my-2', $columnClass]]

// After
'#item_attributes' => ['class' => ['product-item', 'columns-' . $columns]]

abhishek@kumar, yeah, thanks, that's exactly the plan - get rid of all Bootstrap dependency in the PHP code and keep it only in the default templates, because we need to use any frontend framework to design the default output, and we've chosen Bootstrap for it.

Implemented.