pg_rewind tests increase timeout for promotion to 75 seconds.

Few recent failures on concourse reveal that if workers are super
slow, promotion can take time and test unnecessarily flakes due to
timeout. In current instance took more than 1 min for promotion to
complete.

src/bin/pg_rewind/sql/config_test.sh

@@ -118,6 +118,6 @@ function wait_until_standby_streaming_state {
    do
       PGOPTIONS=${PGOPTIONS_UTILITY} $STANDBY_PSQL -c "SELECT state FROM pg_stat_replication;" | grep 'streaming' > /dev/null && break
       retry=$[$retry-1]
-      sleep 0.2
+      sleep 0.5
    done
 }