Increase Jest timeout on CI to 5 seconds

This sets the test timeout for Jest to 5000ms on CI while keeping it at 500ms locally.

see https://gitlab.com/gitlab-org/gitlab-ce/issues/60710#note_178632051

• closes https://gitlab.com/gitlab-org/gitlab-ce/issues/61235
• closes https://gitlab.com/gitlab-org/gitlab-ce/issues/61905
• closes https://gitlab.com/gitlab-org/gitlab-ce/issues/62855