Remove remnants of clumsy old URI state handling from workboards

Summary:
Depends on D20636. Ref T4900. Previously, some workflows didn't know how to identify the default state for the board, so they needed explicit ("force") parameters.

Everything uses the same state management code now so we can rip out the old stuff.

Test Plan: Changed board filters, selected a custom filter, edited a custom filter.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T4900

Differential Revision: https://secure.phabricator.com/D20637