[bugfix] always go through status parent dereferencing on isNew, even on data-race

[NyaaaWhatsUpDoc]

Description

As the title says really. This isn't ideal, but it's the only (easy) way of handling this right now, without performing a parent dereference within mutex lock and possibly risk lock-ups if there's any threads that end up self-referencing. This shouldn't happen too often so performance impact shouldn't be much, especially as all of those statuses will also just return fetched_at as too new (all of which will be cache hits).

Also removes the dereference account step after dereferencing status in the fedi API worker, as to reach that point the account must already have been dereferenced / refreshed.

Closes #2396

Checklist

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[tsmethurst]

Nice one!