in favor of stock StartsWith and HasSubstr matchers provided by gmock. BUG=None Change-Id: Ib7e9a0ac73d506c349b8ec102dd4236767077d61 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/334460 Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org> Commit-Queue: Philipp Hancke <phancke@microsoft.com> Reviewed-by: Harald Alvestrand <hta@webrtc.org> Cr-Commit-Position: refs/heads/main@{#41531}