Add cancel button to forms that didn't have one already

app/views/profiles/preferences/show.html.haml

app/views/projects/deploy_keys/_form.html.haml

app/views/projects/edit.html.haml

app/views/projects/labels/_form.html.haml

app/views/projects/merge_requests/_new_compare.html.haml

app/views/projects/runners/edit.html.haml

app/views/projects/services/_form.html.haml

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

app/views/shared/snippets/_form.html.haml

features/steps/project/forked_merge_requests.rb

features/steps/project/issues/issues.rb

features/steps/project/merge_requests.rb