Move EligibleForSpending into GroupOutputs

Summary:

Instead of filtering after the OutputGroups have been made, do it as they are being made.

This is a partial backport core#20040:
https://github.com/bitcoin/bitcoin/pull/20040/commits/d895e98b594b873f3d34c8ba63e9b55125d51b5a

Depends on D14019.

Test Plan:

ninja all check

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D14020