Tez UI: Task logs url use in-progress url causing various errors

The download link when pointing to the in-progress URL will not work in most cases as the downloaded page is the link to the NM which internally redirects to the job history. This means that the downloaded file will not have any actual log contents.

Possible solutions:

• only show download button when an application has completed. Please note that this is for when a yarn app has completed. A completed DAG has no guarantee that its logs are available for download.
• download link should always only rely on completed log url and never on in-progress url
• view logs link can always point to in-progress url as it will automatically redirect to the jobhistory logs url if the container has completed.