chore(*): add mathlib4 synchronization comments (#18535)
Regenerated from the [port status wiki page](https://github.com/leanprover-community/mathlib/wiki/mathlib4-port-status).
Relates to the following files:
* `algebra.algebra.bilinear`
* `algebra.algebra.pi`
* `algebra.algebra.tower`
* `category_theory.limits.filtered`
* `category_theory.limits.preserves.basic`
* `category_theory.limits.preserves.limits`
* `category_theory.limits.shapes.wide_pullbacks`
* `combinatorics.simple_graph.acyclic`
* `combinatorics.simple_graph.connectivity`
* `combinatorics.simple_graph.regularity.uniform`
* `data.nat.digits`
* `linear_algebra.basis.bilinear`
* `linear_algebra.tensor_product`
