Is this question asking specifically about an Arcane Trickster or Eldritch Knight a duplicate of the more general question which does not specify any class or subclass?
It is a duplicate that should be closed.
We will examine these questions according to the three duplicate criteria
It's the same question, or Question A is already covered obviously as a subset of Question B. Obvious here means I can tell at a glance it's there.
In this case, Question B, the general case, does not specify any class or subclass. Naturally, the scope of the question then includes all classes and subclasses, thereby covering Question A in its scope. One might object, "it isn't obvious that Arcane Trickster or Eldritch Knight are covered by Question B." It's not obvious that any particular class or subclass or subclass are covered by it because it is obvious that the question concerns any and all classes and subclasses having spell slots.
Question B has an obvious answer to Question A. Obvious here means I get a straightforward answer without hard searching — a couple of sentences buried in the middle of a post, or an answer which only sort of implies an answer to Question A, doesn't count as obvious.
Question B has an obvious answer to Question A. Half of this answer is dedicated to dealing with the special case of Question A and is clearly sign posted with a header.
There is not some strong compelling reason to covering Question A alone, separately from Question B. (If the above bullet points are met this rarely happens.)
There is now no reason to leave Question A open. When Question A was originally asked, Criterion 2 was not satisfied, but it has since been satisfied in the linked answer.