Fixes #34396 - job report tweaks

This change adds few enhancements to the existing Job report. The report
is used with REX plugin, which has a button "Create Report" in job
detail page. Clicking that button takes user to the render report form
and fills in the job id input.

The enhancements:
1) rename the template to Job - Invocation Report to be more consistent
with other report templates
2) Add missing `-` to closing `%>` erb tags to avoid empty lines in the
output
3) don't fail on ended_at being nil, meaning on jobs that are still
running, instead use empty value in such case
4) the format_time macro keeps month and day as two digits

The follow up is necessary in the REX plugin so the setting default
value reflects the new name.