[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>

searx/answerers/__init__.py

@@ -1,25 +1,30 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
+# pylint: disable=missing-module-docstring
+
+import sys
 from os import listdir
 from os.path import realpath, dirname, join, isdir
-from searx.utils import load_module
 from collections import defaultdict
 
+from searx.utils import load_module
 
 answerers_dir = dirname(realpath(__file__))
 
 
 def load_answerers():
-    answerers = []
+    answerers = []  # pylint: disable=redefined-outer-name
+
     for filename in listdir(answerers_dir):
         if not isdir(join(answerers_dir, filename)) or filename.startswith('_'):
             continue
         module = load_module('answerer.py', join(answerers_dir, filename))
-        if not hasattr(module, 'keywords') or not isinstance(module.keywords, tuple) or not len(module.keywords):
-            exit(2)
+        if not hasattr(module, 'keywords') or not isinstance(module.keywords, tuple) or not module.keywords:
+            sys.exit(2)
         answerers.append(module)
     return answerers
 
 
-def get_answerers_by_keywords(answerers):
+def get_answerers_by_keywords(answerers):  # pylint:disable=redefined-outer-name
     by_keyword = defaultdict(list)
     for answerer in answerers:
         for keyword in answerer.keywords: