Reduce the total number of calls to getCallsign()

Summary: Ref T4245. Before doing any hard work here, we can dramatically reduce the number of things that make calls to `getCallsign()` to make navigating things easier. Almost all of them only care about a monogram, URI, or display name.

Test Plan:
- Searched for `r uniquename` in jump nav.
- Ran `bin/repository reparse --change rXXXyyyyy --trace`, observed query against bad commit table.
- Ran `bin/search index rXXXyyyy --trace --force`, observed proper title when indexing commit.
- Browed repository list, saw proper `rXXX` and appropriate link targets.
- Mentioned `rXXX` in Remarkup, got a link to the right place.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T4245

Differential Revision: https://secure.phabricator.com/D14923

src/applications/repository/query/PhabricatorRepositorySearchEngine.php

@@ -155,15 +155,15 @@ final class PhabricatorRepositorySearchEngine
         ->setUser($viewer)
         ->setObject($repository)
         ->setHeader($repository->getName())
-        ->setObjectName('r'.$repository->getCallsign())
-        ->setHref($this->getApplicationURI($repository->getCallsign().'/'));
+        ->setObjectName($repository->getMonogram())
+        ->setHref($repository->getURI());
 
       $commit = $repository->getMostRecentCommit();
       if ($commit) {
         $commit_link = DiffusionView::linkCommit(
-            $repository,
-            $commit->getCommitIdentifier(),
-            $commit->getSummary());
+          $repository,
+          $commit->getCommitIdentifier(),
+          $commit->getSummary());
         $item->setSubhead($commit_link);
         $item->setEpoch($commit->getEpoch());
       }