update(userspace/engine): remove warnings for missing exceptions

We want users to continue using rules without having to use exceptions.
Exceptions are an additional feature for more advanced use-cases, having
a warning in there will mean that everyone now adds an empty exception
to avoid the warning.

Co-Authored-By: Leonardo Grasso <me@leonardograsso.com>
Signed-off-by: Lorenzo Fontana <lo@linux.com>

test/rules/exceptions/rule_without_exception.yaml

@@ -1,21 +0,0 @@
-#
-# Copyright (C) 2020 The Falco Authors.
-#
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-#
-- rule: My Rule
-  desc: Some desc
-  condition: evt.type=open and proc.name=cat
-  output: Some output
-  priority: error