## Problem
All tests have already been parametrised by Postgres version and build
type (to have them distinguishable in the Allure report), but despite
it, it's anyway required to have DEFAULT_PG_VERSION and BUILD_TYPE env
vars set to corresponding values, for example to
run`test_timeline_deletion_with_files_stuck_in_upload_queue[release-pg14-local_fs]`
test it's required to set `DEFAULT_PG_VERSION=14` and
`BUILD_TYPE=release`.
This PR makes the test framework pick up parameters from the test name
itself.
## Summary of changes
- Postgres version and build type related fixtures now are
function-scoped (instead of being sessions scoped before)
- Deprecate `--pg-version` argument in favour of DEFAULT_PG_VERSION env
variable (it's easier to parse)
- GitHub autocomment now includes only one command with all the failed
tests + runs them in parallel
