perf(adjoint): vectorize PolySlab sidewall patch collection

Author: yaugenst-flex

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 - Removed validator that would warn if `PerturbationMedium` values could become numerically unstable, since an error will anyway be raised if this actually happens when the medium is converted using actual perturbation data.
+- Improved performance of adjoint gradient computation for `PolySlab` and `Cylinder` geometries through vectorized sidewall patch collection (~4x speedup).
 
 ### Fixed