updated tests to comply with the corresponding EE branch

spec/features/discussion_comments/commit_spec.rb

 require 'spec_helper'
 
-describe 'Discussion Comments Commit', :js do
+describe 'Thread Comments Commit', :js do
   include RepoHelpers
 
   let(:user) { create(:user) }
@@ -14,5 +14,5 @@ describe 'Discussion Comments Commit', :js do
     visit project_commit_path(project, sample_commit.id)
   end
 
-  it_behaves_like 'discussion comments', 'commit'
+  it_behaves_like 'thread comments', 'commit'
 end

spec/features/discussion_comments/issue_spec.rb

 require 'spec_helper'
 
-describe 'Discussion Comments Issue', :js do
+describe 'Thread Comments Issue', :js do
   let(:user) { create(:user) }
   let(:project) { create(:project) }
   let(:issue) { create(:issue, project: project) }
@@ -12,5 +12,5 @@ describe 'Discussion Comments Issue', :js do
     visit project_issue_path(project, issue)
   end
 
-  it_behaves_like 'discussion comments', 'issue'
+  it_behaves_like 'thread comments', 'issue'
 end

spec/features/discussion_comments/merge_request_spec.rb

 require 'spec_helper'
 
-describe 'Discussion Comments Merge Request', :js do
+describe 'Thread Comments Merge Request', :js do
   let(:user) { create(:user) }
   let(:project) { create(:project, :repository) }
   let(:merge_request) { create(:merge_request, source_project: project) }
@@ -12,5 +12,5 @@ describe 'Discussion Comments Merge Request', :js do
     visit project_merge_request_path(project, merge_request)
   end
 
-  it_behaves_like 'discussion comments', 'merge request'
+  it_behaves_like 'thread comments', 'merge request'
 end

spec/features/discussion_comments/snippets_spec.rb

 require 'spec_helper'
 
-describe 'Discussion Comments Snippet', :js do
+describe 'Thread Comments Snippet', :js do
   let(:user) { create(:user) }
   let(:project) { create(:project) }
   let(:snippet) { create(:project_snippet, :private, project: project, author: user) }
@@ -12,5 +12,5 @@ describe 'Discussion Comments Snippet', :js do
     visit project_snippet_path(project, snippet)
   end
 
-  it_behaves_like 'discussion comments', 'snippet'
+  it_behaves_like 'thread comments', 'snippet'
 end

spec/support/features/discussion_comments_shared_example.rb

-shared_examples 'discussion comments' do |resource_name|
+shared_examples 'thread comments' do |resource_name|
   let(:form_selector) { '.js-main-target-form' }
   let(:dropdown_selector) { "#{form_selector} .comment-type-dropdown" }
   let(:toggle_selector) { "#{dropdown_selector} .dropdown-toggle" }