[swappable] Migrations not following swappable docs

[nemesifier]

Some parts of the migrations are not following the indications of the swappable documentation regarding migrations.

Here we have both the swappable dependency from the migration framework, and the django-swappable-models one:

openwisp-controller/openwisp_controller/geo/migrations/0001_initial.py

Lines 23 to 24 in 830f1ca

	migrations.swappable_dependency(settings.CONFIG_DEVICE_MODEL),
	swapper.dependency('config', 'Device'),

Why is that? Shouldn't we have just the swappable one?

Same here:

openwisp-controller/openwisp_controller/connection/migrations/0001_initial.py

Lines 23 to 24 in 830f1ca

	migrations.swappable_dependency(settings.CONFIG_DEVICE_MODEL),
	swapper.dependency('config', 'Device'),

Can we also take advantage to remove the exclusion of the QA checks from the migrations as did here?
https://github.com/openwisp/openwisp-notifications/pull/115/files#diff-380c6a8ebbbce17d55d50ef17d3cf906L7-L21