Drop redundant flake8 execution from pre-commit

The same is executed via hacking.

Change-Id: I40eb495a63933b003bb15d0e1670931d5e292a0b
Signed-off-by: Takashi Kajinami <kajinamit@oss.nttdata.com>

.pre-commit-config.yaml

@@ -39,15 +39,6 @@ repos:
         exclude: '^(doc|releasenotes|tools)/.*$'
   - repo: local
     hooks:
-      - id: flake8
-        name: flake8
-        additional_dependencies:
-          - hacking>=6.1.0,<6.2.0
-          - neutron-lib
-        language: python
-        entry: flake8
-        files: '^.*\.py$'
-        exclude: '^(doc|releasenotes|tools)/.*$'
       - id: pylint
         name: pylint
         entry: .tox/pep8/bin/pylint