[mod] pylint all files with one profile / drop PYLINT_SEARXNG_DISABLE_OPTION

In the past, some files were tested with the standard profile, others with a
profile in which most of the messages were switched off ... some files were not
checked at all.

- ``PYLINT_SEARXNG_DISABLE_OPTION`` has been abolished
- the distinction ``# lint: pylint`` is no longer necessary
- the pylint tasks have been reduced from three to two

  1. ./searx/engines -> lint engines with additional builtins
  2. ./searx ./searxng_extra ./tests -> lint all other python files

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

tests/unit/test_preferences.py

@@ -1,3 +1,6 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
+# pylint: disable=missing-module-docstring, invalid-name
+
 from searx.locales import locales_initialize
 from searx.preferences import (
     EnumStringSetting,
@@ -12,13 +15,13 @@ from tests import SearxTestCase
 locales_initialize()
 
 
-class PluginStub:
+class PluginStub:  # pylint: disable=missing-class-docstring, too-few-public-methods
     def __init__(self, plugin_id, default_on):
         self.id = plugin_id
         self.default_on = default_on
 
 
-class TestSettings(SearxTestCase):
+class TestSettings(SearxTestCase):  # pylint: disable=missing-class-docstring
     # map settings
 
     def test_map_setting_invalid_default_value(self):
@@ -118,9 +121,9 @@ class TestSettings(SearxTestCase):
         self.assertEqual(set(setting.get_enabled()), set(['plugin1', 'plugin3']))
 
 
-class TestPreferences(SearxTestCase):
+class TestPreferences(SearxTestCase):  # pylint: disable=missing-class-docstring
     def test_encode(self):
-        from searx.preferences import Preferences
+        from searx.preferences import Preferences  # pylint: disable=import-outside-toplevel
 
         pref = Preferences(['simple'], ['general'], {}, [])
         url_params = (