Remove `return` keywords from `MigrationPreferenceInitializer`
Disable MigrationPreferenceInitializer in UI less environment

This commit prevents possible exceptions that are thrown in an UI less
environment like the test suite because this component relies on UI
classes.
Merge pull request #675 from sschaef/t-non-ui-save-migration-manager

Disable MigrationPreferenceInitializer in UI less environment