Enables the AIChatConversationAPIV2 feature at 100% for nightly users on Windows, Mac, Linux, Android, and iOS starting from version 145.1.89.73.
Meta feature issue: brave/brave-browser#50965

Future plan:
1.89.x in Beta: 0% -> QA verification on search tools in 1.89.x -> 50% -> wait for 1 day -> 100%
1.89.x in Release: 0%->10%->25%->50%->100% increasing per day if no major issues