Add btn-default class to button in project breadcrumb

app/views/projects/_find_file_link.html.haml

-= link_to project_find_file_path(@project, @ref), class: 'gl-button btn shortcuts-find-file', rel: 'nofollow' do
+= link_to project_find_file_path(@project, @ref), class: 'gl-button btn btn-default shortcuts-find-file', rel: 'nofollow' do
   = _('Find file')

app/views/projects/blob/_breadcrumb.html.haml

@@ -23,13 +23,13 @@
     - if blob.readable_text?
       - if blame
         = link_to 'Normal view', project_blob_path(@project, @id),
-            class: 'gl-button btn'
+            class: 'gl-button btn btn-default'
       - else
         = link_to 'Blame', project_blame_path(@project, @id),
-            class: 'gl-button btn js-blob-blame-link' unless blob.empty?
+            class: 'gl-button btn btn-default js-blob-blame-link' unless blob.empty?
 
     = link_to 'History', project_commits_path(@project, @id),
-        class: 'gl-button btn'
+        class: 'gl-button btn btn-default'
 
     = link_to 'Permalink', project_blob_path(@project,
-        tree_join(@commit.sha, @path)), class: 'gl-button btn js-data-file-blob-permalink-url'
+        tree_join(@commit.sha, @path)), class: 'gl-button btn btn-default js-data-file-blob-permalink-url'

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

@@ -3,7 +3,7 @@
 - if !project.empty_repo? && can?(current_user, :download_code, project)
   - archive_prefix = "#{project.path}-#{ref.tr('/', '-')}"
   .project-action-button.dropdown.inline>
-    %button.gl-button.btn.has-tooltip{ title: s_('DownloadSource|Download'), 'data-toggle' => 'dropdown', 'aria-label' => s_('DownloadSource|Download'), 'data-display' => 'static', data: { qa_selector: 'download_source_code_button' } }
+    %button.gl-button.btn.btn-default.has-tooltip{ title: s_('DownloadSource|Download'), 'data-toggle' => 'dropdown', 'aria-label' => s_('DownloadSource|Download'), 'data-display' => 'static', data: { qa_selector: 'download_source_code_button' } }
       = sprite_icon('download')
       %span.sr-only=  _('Select Archive Format')
       = sprite_icon("chevron-down")

changelogs/unreleased/yo-btn-default-repo.yml

+---
+title: Add btn-default class to button in project breadcrumb
+merge_request: 51910
+author: Yogi (@yo)
+type: fixed

ee/app/views/projects/tree/_lock_link.html.haml

-= lock_file_link(html_options: { class: "btn path-lock js-path-lock js-hide-on-root hidden gl-button" })
+= lock_file_link(html_options: { class: "btn btn-default path-lock js-path-lock js-hide-on-root hidden gl-button" })