[roll third_party/pigweed] pw_system: Move snapshot proto call to namespace

Fix call to ThreadSnapshotService to include the .proto namespace.

Original-Bug: b/289376657

Test: device.snapshot_peak_stack_usage() from pw_console works on
      stm32f429i

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/153651

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 148e931089cf332..d851dcbb531bb41
Roller-URL: https://ci.chromium.org/b/8776920564761531969
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I43753852e11cdb665af34c43a448430ea1ab1c0b
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/153731
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 148e931..d851dcb 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 148e931089cf332a091a63e0013557805878cbc7
+Subproject commit d851dcbb531bb412aff63acf0f795885f21a1013