Verify python source files with flake8 #3155

Job	Run time
build-arm64	47m 10s
build-ceph	1m 46s
build	9m 37s
atom	34m 21s
discovery (container)	4m 12s
demo (unsecured)	4m 36s
discovery (embedded)	3m 55s
ha (sanity)	3m 51s
pytest (cli)	2m 36s
demo (psk)	5m 20s
ha (no_huge)	4m 5s
pytest (cli_change_lb)	8m 7s
demo (dhchap)	5m 26s
ha (ns_lb_change)	3m 50s
pytest (cli_change_keys)	2m 51s
ha (no_subsystems)	2m 44s
pytest (cli_change_ns_visibility)	3m 3s
ha (auto_load_balance)	19m 55s
pytest (state)	2m 35s
ha (state_transitions)	4m 42s
pytest (multi_gateway)	2m 37s
ha (state_transitions_both_gws)	6m 20s
pytest (server)	3m 8s
ha (state_transitions_loop)	20m 29s
pytest (grpc)	2m 58s
ha (state_transitions_rand_loop)	25m 22s
pytest (omap_lock)	3m 53s
ha (late_registration)	4m 24s
pytest (log_files)	3m 11s
ha (late_registration_loop)	9m 30s
pytest (nsid)	3m 23s
ha (4gws)	8m 36s
pytest (psk)	3m 26s
ha (4gws_loop)	10m 57s
pytest (dhchap)	2m 26s
ha (4gws_create_delete)	9m 0s
ha (4gws_create_delete_loop)	11m 25s
ha (namespaces)	12m 6s
ha (namespaces_loop)	21m 45s
ha (mtls)	3m 43s
ha (notify)	2m 46s
ha (ceph_status)	2m 10s
ha (blocklist)	2m 45s
ha (main_exit)	1m 51s
push-devel-image-to-ceph-registry	0s
push-images-to-ceph-registry	0s
	5h 52m 53s

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