chore(ci): allow 'Reland' PR title prefix (#18273)

tools/verify_pr_title.js

@@ -28,6 +28,9 @@ const validPrefixes = [
   // allow Revert PRs because it allows us to remove the landed
   // commit from the generated changelog
   "Revert ",
+  // allow Reland PRs because when editing the changelog, it helps us identify
+  // commits that were reverted, but then relanded
+  "Reland ",
   // Allow landing breaking changes that are properly marked
   "BREAKING",
 ];