Correct usage of the have_link matcher

The second option to this matcher should be an options hash; anything
else is just ignored, which can lead to false positives in tests.

We see one such false positive in the "Learn more" link test in
`spec/features/projects/blobs/blob_show_spec.rb`.

spec/features/projects/blobs/blob_show_spec.rb

@@ -533,7 +533,7 @@ describe 'File blob', :js do
         expect(page).to have_content('This project is licensed under the MIT License.')
 
         # shows a learn more link
-        expect(page).to have_link('Learn more', 'http://choosealicense.com/licenses/mit/')
+        expect(page).to have_link('Learn more', href: 'http://choosealicense.com/licenses/mit/')
       end
     end
   end
@@ -566,10 +566,10 @@ describe 'File blob', :js do
         expect(page).to have_content('This project manages its dependencies using RubyGems and defines a gem named activerecord.')
 
         # shows a link to the gem
-        expect(page).to have_link('activerecord', 'https://rubygems.org/gems/activerecord')
+        expect(page).to have_link('activerecord', href: 'https://rubygems.org/gems/activerecord')
 
         # shows a learn more link
-        expect(page).to have_link('Learn more', 'http://choosealicense.com/licenses/mit/')
+        expect(page).to have_link('Learn more', href: 'https://rubygems.org/')
       end
     end
   end

spec/views/help/index.html.haml_spec.rb

@@ -21,7 +21,7 @@ describe 'help/index' do
       render
 
       expect(rendered).to match '8.0.2'
-      expect(rendered).to have_link('abcdefg', 'https://gitlab.com/gitlab-org/gitlab-ce/commits/abcdefg')
+      expect(rendered).to have_link('abcdefg', href: 'https://gitlab.com/gitlab-org/gitlab-ce/commits/abcdefg')
     end
   end
 
@@ -29,7 +29,7 @@ describe 'help/index' do
     it 'is visible to guests' do
       render
 
-      expect(rendered).to have_link(nil, help_instance_configuration_url)
+      expect(rendered).to have_link(nil, href: help_instance_configuration_url)
     end
   end