Add links to browser performance issues: web_project_commit, web_project_file_blame, web_project_file_rendered, web_project_files, web_project_issue

The MR adds links to the newly created browser performance issues:

• gitlab-org/gitlab#331443 - web_project_commit
• gitlab-org/gitlab#331444 (closed) - web_project_commit
• gitlab-org/gitlab#331445 (closed) - web_project_file_blame
• gitlab-org/gitlab#331446 - web_project_file_blame
• gitlab-org/gitlab#331447 - web_project_file_rendered
• gitlab-org/gitlab#331448 (closed) - web_project_file_rendered
• gitlab-org/gitlab#331449 (closed) - web_project_files
• gitlab-org/gitlab#331450 - web_project_issue

Tightens up thresholds for web_project_commits, web_project_issues and web_user tests.

Related to #5 (closed)