Reminder: clean up without_legacy_printoptions test decorator #16491

This is an issue to remind ourselves to remove @without_legacy_printoptions everywhere it's used as well as its definition when it's not needed anymore

What should happen first (ideally, in this order):

• numpy 2 compat: tests failing with default print options #16423
• Adjust to numpy dev scalar format #15065

For context I don't expect this issue to ever become urgent: this decorator will become a noop when #15065 is merged, but that's also the reason why it should be removed in the first place :)