Merge branch 'always-show-download-button' into 'master'

Project download buttons always show

## What does this MR do?
Removes `hidden-xs hidden-sm` classes from `download-button` so it doesn’t hide itself individually from the rest of the `project-repo-buttons` block

## Why was this MR needed?
Fixes #23960. Not sure why this element had these classes in the first place, but at the very least we shouldn’t be hiding the Download button at the `hidden-sm` threshold since that’s still fairly large viewport and users with viewports of that size likely still want to download source code.

## Screenshots (if relevant)
Screenshots taken at ~830px width
__Before__
![before](/uploads/21955cf7a12f6eb9cfef96bbb27b7110/before.png)

__After__
![after](/uploads/c082884f225184d56a920adbc0a0a732/after.png)

## What are the relevant issue numbers?
#23960

See merge request !7405

app/views/projects/buttons/_download.html.haml

 - if !project.empty_repo? && can?(current_user, :download_code, project)
-  %span{class: 'hidden-xs hidden-sm download-button'}
+  %span{class: 'download-button'}
     .dropdown.inline
       %button.btn{ 'data-toggle' => 'dropdown' }
         = icon('download')

changelogs/unreleased/always-show-download-button.yml

+---
+title: Project download buttons always show
+merge_request: 7405
+author: Philip Karpiak