[PolicyLogs] Enabling PolicyLogsPageIOS flag in Test Config

This CL adds the PolicyLogsPageIOS feature to
`fieldtrial_testing_config` so that all tests that run on bots and debug
builds have the feature enabled to catch any potential issues.

Bug: b/266471087
Change-Id: Iea50217112183046855af4d89964c6787c7c18e0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4343969


Reviewed-by: Fabio Tirelo <ftirelo@chromium.org>
Commit-Queue: Salma Elmahallawy <esalma@google.com>
Cr-Commit-Position: refs/heads/main@{#1118648}