Simplify validate-pr-target-branch: skip validation for branch PRs (same repo)

Co-authored-by: AndriySvyryd <6539701+AndriySvyryd@users.noreply.github.com>
Agent-Logs-Url: https://github.com/dotnet/efcore/sessions/9fa9efe5-51a7-419b-bc7a-79c97dd6778c

Author: Copilot

.github/workflows/validate-pr-target-branch.yml

@@ -53,6 +53,12 @@ jobs:
               return;
             }
             
+            // If the PR is from a branch (not a fork), it must be from an internal contributor
+            if (pr.head.repo && pr.head.repo.id === pr.base.repo.id) {
+              console.log('PR is from a branch in the same repo - skipping validation');
+              return;
+            }
+            
             // Check if the user who triggered the action has push permissions
             let hasWriteAccess = false;
             try {