lower instance priority

Stream: general

[Yuyang Zhao]

Why docs#ordered_cancel_comm_monoid.to_contravariant_class_le_left has priority 200 but docs#ordered_cancel_comm_monoid.to_contravariant_class_left and docs#ordered_cancel_comm_monoid.to_contravariant_class_right has normal priority?

[Yaël Dillies]

git blaming will probably give you the answer

[Yuyang Zhao]

#17571 Seems it can have the normal priority.

[Sebastien Gouezel]

Do you have a good reason for this change? I mean, there is probably a (at least heuristic) performance reason if the priority is not standard, so one should check throughly that the change does not have a performance penalty

[Yuyang Zhao]

This instance is added in PR #16445. Seems there is no reason to make its priority different from the other 2.

[Yaël Dillies]

I remember following the priority from another instance.

[Yuyang Zhao]

Maybe the priority of the other two instances should be lowered too?