Merge branch 'yo-gl-button-issues' into 'master'

Apply new GitLab UI for subscribe buttons in issues

See merge request gitlab-org/gitlab!52401

app/views/shared/issuable/_feed_buttons.html.haml

-= link_to safe_params.merge(rss_url_options), class: 'btn btn-svg has-tooltip', data: { container: 'body', testid: 'rss-feed-link' }, title: _('Subscribe to RSS feed') do
+= link_to safe_params.merge(rss_url_options), class: 'btn gl-button btn-default has-tooltip', data: { container: 'body', testid: 'rss-feed-link' }, title: _('Subscribe to RSS feed') do
   = sprite_icon('rss', css_class: 'qa-rss-icon')
-= link_to safe_params.merge(calendar_url_options), class: 'btn has-tooltip', data: { container: 'body' }, title: _('Subscribe to calendar') do
+= link_to safe_params.merge(calendar_url_options), class: 'btn gl-button btn-default has-tooltip', data: { container: 'body' }, title: _('Subscribe to calendar') do
   = sprite_icon('calendar')

app/views/shared/issuable/csv_export/_button.html.haml

 - if current_user
-  %button.csv_download_link.btn.gl-button.has-tooltip{ title: _('Export as CSV'),
+  %button.csv_download_link.btn.gl-button.btn-default.has-tooltip{ title: _('Export as CSV'),
     data: { toggle: 'modal', target: ".#{issuable_type}-export-modal", qa_selector: 'export_as_csv_button' } }
     = sprite_icon('export')

changelogs/unreleased/yo-gl-button-issues.yml

+---
+title: Apply new GitLab UI for subscribe buttons in issues
+merge_request: 52401
+author: Yogi (@yo)
+type: other