Replace all "setQueryParam()" calls with "remove/replaceQueryParam()"
Summary: Ref T13250. See D20149. Mostly: clarify semantics. Partly: remove magic "null" behavior.
Test Plan: Poked around, but mostly just inspection since these are pretty much one-for-one.
Reviewers: amckinley
Reviewed By: amckinley
Subscribers: yelirekim
Maniphest Tasks: T13250
Differential Revision: https://secure.phabricator.com/D20154