flake8: adapt to the newer rules

Probably coming from a newer pycodestyle.
Follow along with the earlier sahara changes, see also:
https://review.opendev.org/633912

In a nutshell: fix E305, ignore W504 and W605.

Change-Id: Ica6c9896e937f5a74944717627111271ac24f72a

sahara_plugin_cdh/plugins/cdh/v5_11_0/resources/cdh_config.py

@@ -58,6 +58,7 @@ def write_cfg(cfg, file_name):
     with open(file_name, 'w') as f:
         f.write(to_write)
 
+
 if __name__ == '__main__':
     for service in services:
         process_service(service)

sahara_plugin_cdh/plugins/cdh/v5_13_0/resources/cdh_config.py

@@ -63,6 +63,7 @@ def write_cfg(cfg, file_name):
     with open(file_name, 'w') as f:
         f.write(to_write)
 
+
 if __name__ == '__main__':
     for service in services:
         process_service(service)

tox.ini

@@ -100,7 +100,9 @@ enable-extensions=H904,H106,H203,H204,H205
 # [E402] Module level import not at top of file
 # [E731] Do not assign a lambda expression, use a def
 # [W503] Line break occurred before a binary operator
-ignore=E123,E226,E402,E731,W503
+# [W504] Line break occurred after a binary operator
+# [W605] Invalid escape sequence 'x'
+ignore=E123,E226,E402,E731,W503,W504,W605
 
 [testenv:lower-constraints]
 basepython = python3