* [Archive Migration][Partial] discover apps-management

Comes from elastic#102827

Helps with elastic#108503

Only include the changes under the
test/functional/apps/management folder.

* Remove the index pattern, that the test
creates.

* Drop beforeEach(), in favour of before(),
since there's only one test.

* Drop outdated comment,
drop these three cleanup lines
as the unload should handle it.

* Just keep one cleanup.

Co-authored-by: Kibana Machine <42973632+kibanamachine@users.noreply.github.com>