Adds testcase links to the new share_snippet_spec

Follow up to https://gitlab.com/gitlab-org/gitlab/-/merge_requests/40688

qa/qa/specs/features/browser_ui/3_create/snippet/share_snippet_spec.rb

@@ -17,7 +17,7 @@ module QA
       end
 
       context 'when the snippet is public' do
-        it 'can be shared with not signed-in users' do
+        it 'can be shared with not signed-in users', testcase: 'https://gitlab.com/gitlab-org/quality/testcases/-/issues/1016' do
           snippet
 
           sharing_link = Page::Dashboard::Snippet::Show.perform do |snippet|
@@ -39,7 +39,7 @@ module QA
       end
 
       context 'when the snippet is changed to private' do
-        it 'does not display Embed/Share dropdown' do
+        it 'does not display Embed/Share dropdown', testcase: 'https://gitlab.com/gitlab-org/quality/testcases/-/issues/1015' do
           snippet
 
           Page::Dashboard::Snippet::Show.perform do |snippet|