JCMA doesn't migrate all single project filters by default

Issue Summary

When migrating without using the "cross-project" or 

com.atlassian.jira.migration.export.all.filters

filters that have only one project don't get migrated unless they have share permissions set for the project or they are configured to a board.

Steps to Reproduce

1. Create a project with no boards
2. Create a new private filter that uses only the single project in the JQL
3. Migrate the project

Expected Results

The filter is migrated to the destination regardless of configuration as long as it only references a single project.

Actual Results

The filter is not migrated at all.

Workaround

• Add the project to the filter's share permissions.
• Use the cross-project boards and filters features