roll: third_party/pigweed pw_bluetooth_proxy: Remove ProxyHost gatt send

Downstream clients have moved to using GattNotifyChannel to send.

Original-Bug: 369709521
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/289517
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
Original-Revision: 91b3a63eb9cce3a81180a4fdef5d46644e5e9ea2

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: fb9c8ffd703c05..91b3a63eb9cce3
Roll-Count: 1
Roller-URL: https://cr-buildbucket.appspot.com/build/8715313125868295009
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I649f1ec1ef9b31dfc12837697b9c4e264857511a
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/290152
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
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 fb9c8ff..91b3a63 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit fb9c8ffd703c0583dd903aa055e774a7200c874e
+Subproject commit 91b3a63eb9cce3a81180a4fdef5d46644e5e9ea2