Merge #14460: tests: Improve 'CAmount' tests

Summary:
29ed2d64f6 Improve CAmount tests (Hennadii Stepanov)

Pull request description:

This provides:
  - more `MoneyRange` tests;
  - explicit using of the `CAmount` type.

Tree-SHA512: ca0ad6ccb37909a2a5c11034dc07b316a84c32fb40c6f8b6cfc28ebec72a1de157f31d22e767ae80d70ed06d7296f23870cc5ed0689f34a754ae763d50e23d43

Backport of Core PR14460
https://github.com/bitcoin/bitcoin/pull/14460/

Adjusted for our codebase.

Test Plan:

ninja check

Reviewers: O1 Bitcoin ABC, #bitcoin_abc, Fabien

Reviewed By: O1 Bitcoin ABC, #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D5277