roll: pigweed pw_rpc: Add a test for finding a servers max echo packet size

This CL adds a new test to the pw_rpc benchmark tool.  The new test
searches for a target-side server's maximum allowed echo packet by a
doubling method until the max is found.  It enables accuracy to the
byte level, assuming the server doesn't crash.

Currently, this test is executed as part of the standard tests run
by the benchmark tool.  A future CL will expand the user interface
for selecting and running specific benchmark tests.

This CL also has some incidental comment/code cleanup noticed while
writing.

Test: added unit tests for the new benchmark test.
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/278364
Original-Revision: 6b75be9cf2bc1356bc9625637951e81695536bd1

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: bbbdf7690fead0..6b75be9cf2bc13
Roll-Count: 1
Roller-URL: https://cr-buildbucket.appspot.com/build/8717140553293961569
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I2315b1c74a8e85f05248766462c8dd4f571f31b9
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/quickstart/bazel/+/284973
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
diff --git a/MODULE.bazel b/MODULE.bazel
index 0d8cf8e..0fee9e0 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -41,8 +41,8 @@
     module_name = "pigweed",
     # ROLL: Warning: this entry is automatically updated.
     # ROLL: Last updated 2025-04-19.
-    # ROLL: By https://cr-buildbucket.appspot.com/build/8717206754064722849.
-    commit = "bbbdf7690fead0751c35e8fdc3e936c82f253134",
+    # ROLL: By https://cr-buildbucket.appspot.com/build/8717140553293961569.
+    commit = "6b75be9cf2bc1356bc9625637951e81695536bd1",
     remote = "https://pigweed.googlesource.com/pigweed/pigweed",
 )