Content can be added to staging zones located in dead shuttles

[neelvirdy]

Describe the bug

1. User A uploads small file, shuttle 1 is selected
2. shuttle 1 gets turned off
3. User A uploads any other file to any shuttle or API node
4. content gets pinned on selected node, but gets added to the staging zone located on shuttle 1
5. consolidation of staging zone on shuttle 1 will fail until shuttle 1 is back online

Expected behavior
in (4), if the file is big enough for dealmaking on its own, it should not be added to a staging zone at all. if it is not big enough for dealmaking, a new staging zone on an alive node should be created. if the upload is done directly to a shuttle, the staging zone should be made on that shuttle. if it's through the api node, an alive shuttle with the largest existing staging zone for that user should be selected