chore(*): add mathlib4 synchronization comments (#18416)
Regenerated from the [port status wiki page](https://github.com/leanprover-community/mathlib/wiki/mathlib4-port-status).
Relates to the following files:
* `algebra.order.upper_lower`
* `data.pi.interval`
* `number_theory.class_number.admissible_absolute_value`
* `topology.algebra.order.filter`
* `topology.fiber_bundle.is_homeomorphic_trivial_bundle`
* `topology.hom.open`
