brew-postgresql-upgrade-database: abort upgrade if pg_upgrade fails

* Use dedicated safe_system to raise exception

Closes #31175.

Signed-off-by: Dominyk Tiller <dominyktiller@gmail.com>

cmd/brew-postgresql-upgrade-database.rb

@@ -65,7 +65,7 @@ begin
   initdb_run = true
 
   (var/"log").cd do
-    system "#{bin}/pg_upgrade",
+    safe_system "#{bin}/pg_upgrade",
       "-r",
       "-b", old_bin,
       "-B", bin,