roll: pigweed pw_multibuf: Remove MultiBuf's Chunk iterator wrappers

Instead, use the iterators in MultiBufChunks directly. This avoids
having two different iterator types in one class.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/230893
Original-Revision: e31487f84caccbbfc986d8c6327c278ff1548c7d

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: 6b20a021cf616e..e31487f84caccb
Roller-URL: https://ci.chromium.org/b/8736211388081753441
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: If730b44263dbc363ba607a39013c4788996d9516
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/showcase/sense/+/237219
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/MODULE.bazel b/MODULE.bazel
index cd5ce81..342e67e 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -49,18 +49,18 @@
 git_override(
     module_name = "pigweed",
     # ROLL: Warning: this entry is automatically updated.
-    # ROLL: Last updated 2024-09-20.
-    # ROLL: By https://cr-buildbucket.appspot.com/build/8736234473912704753.
-    commit = "6b20a021cf616e20749c3eeb9cdbf8ebff12dcca",
+    # ROLL: Last updated 2024-09-21.
+    # ROLL: By https://cr-buildbucket.appspot.com/build/8736211388081753441.
+    commit = "e31487f84caccbbfc986d8c6327c278ff1548c7d",
     remote = "https://pigweed.googlesource.com/pigweed/pigweed",
 )
 
 git_override(
     module_name = "pw_toolchain",
     # ROLL: Warning: this entry is automatically updated.
-    # ROLL: Last updated 2024-09-20.
-    # ROLL: By https://cr-buildbucket.appspot.com/build/8736234473912704753.
-    commit = "6b20a021cf616e20749c3eeb9cdbf8ebff12dcca",
+    # ROLL: Last updated 2024-09-21.
+    # ROLL: By https://cr-buildbucket.appspot.com/build/8736211388081753441.
+    commit = "e31487f84caccbbfc986d8c6327c278ff1548c7d",
     remote = "https://pigweed.googlesource.com/pigweed/pigweed",
     strip_prefix = "pw_toolchain_bazel",
 )