[backport#16969] refactor: Remove Qt function to disable menu icons on macOS
[backport#16969] refactor: Remove Qt function to disable menu icons on macOS

Summary:
3eea6a8f2686352a0fd868fee6af42ef1283bdda refactor: Remove Qt function to disable menu icons on macOS (Emil Engler)

Pull request description:

  As menu icons were removed in #16612, this removes an unnecessary function for macOS
  Could this get into v0.19.0?

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Backport of Core [[https://github.com/bitcoin/bitcoin/pull/16969 | PR16969]]

Depends on D8749

Test Plan:
  ninja all

Unfortunately I have no macOS to test

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D8750

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