[bug:ui] Select2 autofilter look is inconsistent with other filters

[nemesifier]

Describe the bug

The auto filter using select2 widget has a different look than the rest of the filters.

I think the look should be consistent.

I don't think this change will cause problems to change forms, but let's double check

Steps To Reproduce
Steps to reproduce the behavior:

1. Go to any admin list page which has the select2 filter, eg: device list in openwisp-controller
2. Click on the select2 filter and notice the difference with other filters

Expected behavior

Consistent look.

[AditiSah05]

Can i work on it
I'll use this approach.

Problem: Select2 autofilters looked different from regular filters (height, borders, positioning).

Solution: Updated CSS/JS to make Select2 filters match regular filter styling:

Fixed height to 1.5rem

Aligned borders, padding, and active states

Corrected dropdown positioning

Updated JS dropdown height to 18.75rem

Files changed:

ow-auto-filter.css - styling consistency

ow-auto-filter.js - dropdown height fix

[nemesifier]

Thanks for participating @AditiSah05, I'd simply focus on the color differences, at least initially, we could end up having the select2 widget look consistent in the filters but inconsistent in change forms, keep in mind that it's used in both situations.

[AditiSah05]

Sure, I can focus on the color differences first. I’ll make sure any changes keep the Select2 widget consistent across both filters and change forms.

[AditiSah05]

Hi, @nemesifier I’ve finished the required changes in the PR. Please take a moment to review it, and feel free to merge if it meets the project requirements. Thank you!