Investigate / fix tests for Pooling

[RichardJCai]

See: https://github.com/cockroachdb/sequelize-cockroachdb/pull/114/files#diff-f62ae05809bb0a6bfc6bd9547344f831634fd05b61f000ca7c61edc9204b4a78R24

// PG emits events to communicate with the pg client.
// CRDB apparently does not emit events like these, needed to compare processID:
// https://github.com/brianc/node-postgres/blob/master/packages/pg/lib/client.js#L185

Investigate / rewrite tests such that we can compare the processID field.