roll: third_party/pigweed Revert "pw_protobuf: Force use of callbacks for oneof"

This reverts commit 53d4032b027055342c7321bef95e8a23e805c74c.

Reason for revert: Downstream dependency issues.

Original change's description:
> pw_protobuf: Force use of callbacks for oneof
>
> pw_protobuf's message structures previously generated each of the
> members of a oneof group as a separate struct member, allowing multiple
> of them to be set to serialize semantically-invalid wire messages.
>
> This replaces oneof struct member generation with a single callback for
> the entire oneof group, allowing the user to encode/decode the desired
> oneof field using the wire stream encoder and decoder.
>
> Change-Id: I2e4f79c5f7d2ec99eb036e0f93a77675a29a625c
> Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/236592
> Reviewed-by: Armando Montanez <amontanez@google.com>
> Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>

TBR=hepler@google.com,frolv@google.com,amontanez@google.com,pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com,android-build-ayeaye@system.gserviceaccount.com

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/242193
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
Original-Revision: f60e87048d40096d7b005f4d40e42872b9bae76e

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: 53d4032b027055..f60e87048d4009
Roll-Count: 1
Roller-URL: https://ci.chromium.org/b/8734054739897688833
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Id82c6649a540ede096b362de473b0a9e0d47a727
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/examples/+/242078
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 53d4032..f60e870 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 53d4032b027055342c7321bef95e8a23e805c74c
+Subproject commit f60e87048d40096d7b005f4d40e42872b9bae76e