We no longer need the Jira proxy settings columns in jira_tracker_data
table as we are using the proxy settings via environment variables.
https://docs.gitlab.com/omnibus/settings/environment-variables.html#setting-custom-environment-variables.

This reverts
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/52119.

We previously ignored the columns during 13.11 with
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/57260.