GitLab Docs: Jira Integrations Content Update

Problem to solve

Update Jira Integrations docs in GitLab docs and boost activation rate by including new features, updated screenshots, and a more streamlined structure.

Further details

Proposal

Who can address the issue

@cfoster3 and @davistye

Other links/references

https://docs.gitlab.com/ee/integration/jira/

https://docs.google.com/document/d/1xjldi659ITWZgb7vOism54unr6o_hId6H5iNtVvGrpc/edit