Merge branch 'jej-use-issuable-finder-instead-of-access-check' into 'security'

Replace issue access checks with use of IssuableFinder

Split from !2024 to partially solve https://gitlab.com/gitlab-org/gitlab-ce/issues/23867

## Which fixes are in this MR?

:warning: - Potentially untested  
:bomb: - No test coverage  
:traffic_light: - Test coverage of some sort exists (a test failed when error raised)  
:vertical_traffic_light: - Test coverage of return value (a test failed when nil used)  
:white_check_mark: - Permissions check tested

### Issue lookup with access check

Using `visible_to_user` likely makes these security issues too. See [Code smells](#code-smells).

- [x] :vertical_traffic_light: app/finders/notes_finder.rb:15 [`visible_to_user`]
- [x] :traffic_light: app/views/layouts/nav/_project.html.haml:73 [`visible_to_user`] [`.count`]
- [x] :white_check_mark: app/services/merge_requests/build_service.rb:84 [`issue.try(:confidential?)`]
- [x] :white_check_mark: lib/api/issues.rb:112 [`visible_to_user`]
  - CHANGELOG: Prevented API returning issues set to 'Only team members' to everyone
- [x] :white_check_mark: lib/api/helpers.rb:126 [`can?(current_user, :read_issue, issue)`] Maybe here too?
- [x] :white_check_mark: lib/gitlab/search_results.rb:53 [`visible_to_user`]

### Previous discussions
- [ ] https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/2024/diffs#b2ff264eddf9819d7693c14ae213d941494fe2b3_128_126
- [ ] https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/2024/diffs#7b6375270d22f880bdcb085e47b519b426a5c6c7_87_87

See merge request !2031

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/gitlab/search_results.rb b/lib/gitlab/search_results.rb
index 2690938fe82..47d8599e298 100644
--- a/lib/gitlab/search_results.rb
+++ b/lib/gitlab/search_results.rb
@@ -50,7 +50,7 @@ module Gitlab
     end
 
     def issues
-      issues = Issue.visible_to_user(current_user).where(project_id: project_ids_relation)
+      issues = IssuesFinder.new(current_user).execute.where(project_id: project_ids_relation)
 
       if query =~ /#(\d+)\z/
         issues = issues.where(iid: $1)