Fix SparseArray._broadcast_type

[martinholters]

Use _promote_op and Broadcast.typestuple instead of
Broadcast.ziptype and Broadcast.ftype.

Broadcasting sparse matrices was rewritten to use Broadcast.ziptype and Broadcast.ftype in 840820d, but those were removed in 02596f9.

Fixes #19580

[martinholters]

CC @pabloferz

[pabloferz]

Thanks. I thought there weren't more uses of ftype and ziptype (should have checked).

I guess the _broadcast_type can be removed replacing its uses by _promote_op + typestuple, given it is short enough.

[pabloferz]

Also, could you add a test so this does not go undetected again?

[martinholters]

Oh, it made the tests fail. I guess each PRs last test ran before the other one was merged, that's why it went undetected. (Yes, our current master fails tests.)

[pabloferz]

I see. I wish there was a mechanism to avoid this kind of issue.

[KristofferC]

https://github.com/servo/homu But IIRC it doesn't support AV which we need.

[andreasnoack]

I'll merge this even though it hasn't been open for long to avoid test failures the whole day. If this needs adjustments, it is better to do from a state where master is not failing.

[andreasnoack]

Bisection suggests that the first problematic commit is 02596f9

cc: @pabloferz

[KristofferC]

For context to above. I previously had this comment here, but moved it to #19421

[Sacha0]

Thanks @martinholters! This change was a planned touchup to #19518, so LGTM.