CSI: use job status not alloc status for plugin updates from summary

[tgross]

Fixes #9810 #10073

When an allocation is updated, the job summary for the associated job is also updated. CSI uses the job summary to set the expected count for controller and node plugins. We incorrectly used the allocation's server status instead of the job status when deciding whether to update or remove the job from the plugins. This caused a node drain or other terminal state for an allocation to clear the expected count for the entire plugin.

Use the job status to guide whether to update or remove the expected count.

Notes for reviewers:

• The actual bug fix is this one-liner: aa583a0
• We missed this bug because the CSI plugin lifecycle state tests incorrectly modeled the updates we received from servers vs those we received from clients, leading to test assertions that passed when they should not. And just generally, the tests were hard to read and understand. I've heavily reworked the tests to clarify each step in the lifecycle of plugin allocations with a subtest. That's all in 2ae8ad2 (also, that diff might be easier to read if you do a side-by-side).
• There's still some odd behavior around plugin GC but I'm leaving that as out-of-scope for this changeset. See Unable to normally stop and purge system job with csi plugin #11758 for one example of that, but we also intentionally delete plugins without instances even if they still had volumes, which seems like a really dubious choice now so I want to follow up on that.

[tgross]

Currently the failing unit tests are because of #12028. I'll rebase on main once that's merged. Done

[shoenig]

LGTM! I really like this test refactoring

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