Make pg_version and build_type regular parameters (#4311)

## 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

test_runner/conftest.py

@@ -1,6 +1,6 @@
 pytest_plugins = (
     "fixtures.pg_version",
-    "fixtures.allure",
+    "fixtures.parametrize",
     "fixtures.neon_fixtures",
     "fixtures.benchmark_fixture",
     "fixtures.pg_stats",