After "Request Review", move revisions with voided "Accepts" into "Ready to Review", not "Waiting on Other Reviewers"

Summary:
Depends on D18756. Fixes T12539. See PHI190. Currently, when this occurs:

• Alice accepts.
• Bailey requests review.
• Alice views her dashboard.

...the revision appears in "Waiting on Other Reviewers" (regardless of whether other reviewers actually exist or not).

Instead, ignore these voided/non-current accepts and let the revisions appear in "Ready to Review", which is more natural.

Test Plan: Went through the steps above. On master, saw revision in "Waiting on Other Reviewers". After patch, saw it in "Ready to Review".

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T12539

Differential Revision: https://secure.phabricator.com/D18757