roll: third_party/pigweed: pw_bluetooth_sapphire: Remove unnecessary handle tracking

Discoveriing a handle for the service changed characteristic is used to
decide whether to attempt to send indications, but is never cleared when
there are no subscribers, so will likely be on after the systems runs
for any reasonable length of time. Instead continue to use the set of
subscribed peers directly.

Test: code removal only; fx test bt-host-gatt-tests
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1009175
GitOrigin-RevId: 01c53083ebf40906508a6126e143651a8c5f94db
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/235316
Docs-Not-Needed: Ben Lawson <benlawson@google.com>

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: d63a18b6fb65234..55ff480e6aaddb9
Roller-URL: https://ci.chromium.org/b/8736956832625390353
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I347290df96f3cdc644e79b341459947d272161b7
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/235487
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index d63a18b..55ff480 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit d63a18b6fb65234b4f778e1e13812ee134464f7e
+Subproject commit 55ff480e6aaddb955fdc4bfbc39f18706ccf340d