[roll third_party/pigweed] pw_transfer: Extend write tests

Extends transfer write integration test cases to cover write test cases
covered by the legacy test infrastructure.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/97580

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 3be713d52f7a1bd..e38534ec269996f
Roller-URL: https://ci.chromium.org/b/8811445571838499121
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8811445571838499121
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I6533531e38434e14413d9f9d3f6b1cde0ed971f5
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/97940
Bot-Commit: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
Commit-Queue: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 3be713d..e38534e 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 3be713d52f7a1bd6f12aa02d5850ab58bcfa332d
+Subproject commit e38534ec269996ff913ae4beadcb3d37cb542715