Improve test performance

Issue created to track changes we made to increase test times after the findings on https://github.com/ClickHouse/dbt-clickhouse/issues/499

Currently we have two types of test depending on where the CH cluster is located:
- `test_matrix.yml`: Uses a local CH cluster inside a docker-compose cluster. Currently we execute in parallel a matrix of tests with dimensions: CH version and Python version. One extra dimension is done serially in each execution: connection being done with HTTP or Native protocols. Total time per job is around 10 minutes. this is not an issue right now but any improvement would be welcome
- `test_cloud.yml`: Uses a CH cluster hosted in CH cloud. Currently these tests are not being used as we have found some problems that made these tests took too much time (>2h with a lot of flakyness):
- The CH Cloud cluster was already overloaded.
- The DBT test cannot be currently run in parallel against the same CH cloud instance as some test were colliding between them.

Pending improvements:
- Use a new CH Cloud cluster (we are working on it right now)
- Test a way to be able to execute the CH Cloud test in different clusters (also being worked)
- Be able to execute test in parallel: in progress, it will take time.

Start by reviewing test_matrix.yml and test_cloud.yml, along with the findings in issue 499, to understand the current matrix dimensions, cluster setup, and test collisions. Measure the existing test behavior before changing it; done means the cloud tests can use the new cluster setup reliably and run in parallel without collisions or excessive runtime.

Written by the indexing model from the issue text.