Remove explode-ukin cruft

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Merge pull request #847 from rjc123/newmappings

Config changes for upcoming transitions.
Merge pull request #848 from rjc123/newmappings

Valid tests and go-live configuration changes
Merge pull request #846 from alphagov/remove_ukin_cruft

Remove explode-ukin cruft
Change dates for all BIS legacy domains