chore(*): add mathlib4 synchronization comments (#19185)
Regenerated from the [port status wiki page](https://github.com/leanprover-community/mathlib/wiki/mathlib4-port-status).
Relates to the following files:
* `algebra.category.Group.subobject`
* `analysis.analytic.composition`
* `analysis.convex.intrinsic`
* `analysis.inner_product_space.two_dim`
* `analysis.special_functions.japanese_bracket`
* `category_theory.differential_object`
* `geometry.euclidean.angle.oriented.basic`
* `measure_theory.function.conditional_expectation.ae_measurable`
* `order.category.BddOrd`
* `order.category.Semilat`
* `ring_theory.polynomial.hermite.basic`
* `ring_theory.polynomial.hermite.gaussian`
* `ring_theory.ring_hom.integral`
* `ring_theory.ring_hom_properties`
