1. Remove deprecated support for direct construction of MergeHistory
2. Store reading from the database inside the constructor.
3. Remove ::checkPermissions, deprecated since 1.36
Change-Id: I523d72ab7cb56c76f5d17fb51436fb356441d791
Replaces the removed tests for MovePageFactory and
RollbackPageFactory, which used FactoryArgTestTrait
Change-Id: I53669590c4aa0ca12d0839e5dde9068abbaa59fb