Bump third_party/silabs/matter_support from a4436ce to f21ada8 (#1283)

Bumps [third_party/silabs/matter_support](https://github.com/SiliconLabsSoftware/matter_support) from `a4436ce` to `f21ada8`.
- [Commits](SiliconLabsSoftware/matter_support@a4436ce...f21ada8)

---
updated-dependencies:
- dependency-name: third_party/silabs/matter_support
  dependency-version: f21ada885191e51e4c4cf8e7c1e11b36622357cc
  dependency-type: direct:production
...

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