[roll third_party/pigweed] pw_transfer: Temporarily disable broken integration test

Disables a test which is known to break while the cause can be
investigated. Additionally, adds some checking around transfer test
cleanup which has resulted in flakes.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/194850

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: ea93eb586cad181..7b799c29f0f0522
Roller-URL: https://ci.chromium.org/b/8754366004250832273
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ic0a40bea1b3c8d6c4214fcbe7348a2a38a98f14a
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/194851
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 ea93eb5..7b799c2 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit ea93eb586cad181b86471d519c68f1093b41e7e9
+Subproject commit 7b799c29f0f05229c1ed8cb7dae707c7cc17ca09