Disable connection logging in pgbouncer by default (#10118)

It can produce a lot of logs, making pgbouncer itself consume all CPU in
extreme cases. We saw that happen in stress testing.

compute/etc/pgbouncer.ini

@@ -19,3 +19,10 @@ max_prepared_statements=0
 admin_users=postgres
 unix_socket_dir=/tmp/
 unix_socket_mode=0777
+
+;; Disable connection logging. It produces a lot of logs that no one looks at,
+;; and we can get similar log entries from the proxy too. We had incidents in
+;; the past where the logging significantly stressed the log device or pgbouncer
+;; itself.
+log_connections=0
+log_disconnections=0