fix: [3.x] failing phpunit test

[millnut]

What does this change?

Fixes #879 the following error on the workflow tests

1) Drupal\Tests\localgov\Functional\LocalGovUpdateTest::testUpdate
There should be no errors in configuration 'core.entity_view_display.geo_entity.address.default'. Errors:
Schema key core.entity_view_display.geo_entity.address.default:content.location.settings.leaflet_markercluster.excluded failed with: missing schema

Failed asserting that Array &0 (
    'core.entity_view_display.geo_entity.address.default:content.location.settings.leaflet_markercluster.excluded' => 'missing schema'
) is true.

and then following errors, e.g.

Failed asserting that Array &0 (
    'core.entity_view_display.localgov_geo.address.default:content.location.settings.leaflet_markercluster.excluded' => 'missing schema'
) is true.

Failed asserting that Array &0 (
    'views.view.localgov_directory_channel:display.embed_map.display_options.style.options.view_mode' => 'missing schema'
) is true.

[stephen-cox]

Tests are passing 🙂