Remove unused shouldUse* functions from PhabricatorRepository
Summary:
Calls to private functions `PhabricatorRepository::shouldUseSSH()` and `PhabricatorRepository::shouldUseHTTP()` were removed in https://we.phorge.it/rP29d1115037b84454c4fd186c47f33f162cc337b9.
Call to private function `PhabricatorRepository::shouldUseSVNProtocol()` was removed in https://we.phorge.it/rP575c01373ee77c12b06696b34cfdf43a2eb26c42.
Test Plan: Grep the code; run static code analysis.
Reviewers: O1 Blessed Committers, valerio.bozzolan
Reviewed By: O1 Blessed Committers, valerio.bozzolan
Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno
Differential Revision: https://we.phorge.it/D25786