recorder: reject invalid format and trim model response

To improve genAI user experience, show unsafe content when the response format is invalid, such as wrong format and then trim repeated bullet points.

For repetition config, please refer to colab http://shortn/_oRvXBRKPIW
for more information.

Bug: b:393962362
Test: manually - Run unit test at local and e2e test on DUT

Change-Id: Ifd3ba6e1cd18664361cbe6e2aef6af6323743153
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6246012
Reviewed-by: Pi-Hsun Shih <pihsun@chromium.org>
Commit-Queue: Yuan-Chieh Cheng <yuanchieh@google.com>
Reviewed-by: Jennifer Ling <hsuanling@google.com>
Cr-Commit-Position: refs/heads/main@{#1418450}