Remove no longer used legacy Lister API and update CLI options

Legacy Lister classes from the swh.lister.core mdule are no longer
used in swh-lister codebase so it is time to remove them.

Also remove lister CLI options related to legacy Lister API.

As a consequence, the following requirements are no longer needed:
arrow, SQLAlchemy, sqlalchemy-stubs and testing.postgresql.

Closes T2442

swh/lister/tests/test_cli.py

@@ -1,4 +1,4 @@
-# Copyright (C) 2019-2020  The Software Heritage developers
+# Copyright (C) 2019-2021  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
@@ -7,8 +7,6 @@ import pytest
 
 from swh.lister.cli import SUPPORTED_LISTERS, get_lister
 
-from .test_utils import init_db
-
 lister_args = {
     "cgit": {"url": "https://git.eclipse.org/c/",},
     "phabricator": {
@@ -33,13 +31,11 @@ def test_get_lister(swh_scheduler_config):
     """Instantiating a supported lister should be ok
 
     """
-    db_url = init_db().url()
     # Drop launchpad lister from the lister to check, its test setup is more involved
     # than the other listers and it's not currently done here
     for lister_name in SUPPORTED_LISTERS:
         lst = get_lister(
             lister_name,
-            db_url,
             scheduler={"cls": "local", **swh_scheduler_config},
             **lister_args.get(lister_name, {}),
         )

swh/lister/tests/test_utils.py

@@ -6,7 +6,6 @@ import pytest
 import requests
 from requests.status_codes import codes
 from tenacity.wait import wait_fixed
-from testing.postgresql import Postgresql
 
 from swh.lister.utils import (
     MAX_NUMBER_ATTEMPTS,
@@ -37,18 +36,6 @@ def test_split_range_errors(total_pages, nb_pages):
             next(split_range(total_pages, nb_pages))
 
 
-def init_db():
-    """Factorize the db_url instantiation
-
-    Returns:
-        db object to ease db manipulation
-
-    """
-    initdb_args = Postgresql.DEFAULT_SETTINGS["initdb_args"]
-    initdb_args = " ".join([initdb_args, "-E UTF-8"])
-    return Postgresql(initdb_args=initdb_args)
-
-
 TEST_URL = "https://example.og/api/repositories"