Can't connect to jira
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### Summary
I can't connect gitlab to jira using the integration manager and following these steps: https://docs.gitlab.com/ee/user/project/integrations/jira.html
### Steps to reproduce
Go to a project -> settings -> integrations -> jira
### What is the current *bug* behavior?
It says always: `Test failed` without giving more information:

### What is the expected *correct* behavior?
It should work the configuration or give a better error.
### Relevant logs and/or screenshots
The jira api url i have tried is `https://{my-company}.atlassian.net/rest/api/2/` and also version 3.
### Output of checks
This bug happens on GitLab.com v11.8.1-ee
issue