Disable PR triggers in public AzDo pipeline (#38187)

Co-authored-by: AndriySvyryd <6539701+AndriySvyryd@users.noreply.github.com>

Author: Copilot

azure-pipelines-public.yml

@@ -32,7 +32,7 @@ trigger:
       - feature/*
       - internal/release/*
 
-pr: ['*']
+pr: none
 
 stages:
 - stage: build