fix: storagefsm: Fix error loop on bad event

[magik6k]

Related Issues

Fixes #8307
Fixes #8316

Proposed Changes

If fsm planner returns no error, and 0 processed events, it will be called with the same events, which will cause the same errors, in a loop. This PR makes failed planners still return the number of processed events.

Additional Info

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[jennijuju]

this fixes the kvlog file size increase as well

[Reiers]

#8376

I reproduce the issue - and it still happens.