## Problem
`pg-clients` workflow looks different from the main `build-and-test`
workflow for historical reasons (it was my very first task at Neon, and
back then I wasn't really familiar with the rest of the CI pipelines).
This PR unifies `pg-clients` workflow with `build-and-test`
## Summary of changes
- Rename `pg_clients.yml` to `pg-clients.yml`
- Run the workflow on changes in relevant files
- Create Allure report for tests
- Send slack notifications to `#on-call-qa-staging-stream` channel
(instead of `#on-call-staging-stream`)
- Update Client libraries once we're here
* Add tests for different postgres clients
* test/fixtures: sanitize test name for test_output_dir
* test/fixtures: do not look for etcd before runtime
* Add workflow for testing Postgres client libraries
