Remove all remaining readers and writers for TABLE_COMMIT

Summary: Depends on D20459. Ref T13276. I'll file a followup to actually destroy the table.

Test Plan:
- Grepped for `TABLE_COMMIT`.
- Ran `bin/storage upgrade -f`, got a clean bill of health.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13276

Differential Revision: https://secure.phabricator.com/D20461

src/applications/differential/storage/DifferentialRevision.php

@@ -53,8 +53,6 @@ final class DifferentialRevision extends DifferentialDAO
   private $flags = array();
   private $forceMap = array();
 
-  const TABLE_COMMIT          = 'differential_commit';
-
   const RELATION_REVIEWER     = 'revw';
   const RELATION_SUBSCRIBED   = 'subd';
 
@@ -1021,12 +1019,6 @@ final class DifferentialRevision extends DifferentialDAO
 
       $conn_w = $this->establishConnection('w');
 
-      queryfx(
-        $conn_w,
-        'DELETE FROM %T WHERE revisionID = %d',
-        self::TABLE_COMMIT,
-        $this->getID());
-
       // we have to do paths a little differently as they do not have
       // an id or phid column for delete() to act on
       $dummy_path = new DifferentialAffectedPath();

src/applications/differential/storage/DifferentialSchemaSpec.php

@@ -26,9 +26,12 @@ final class DifferentialSchemaSpec extends PhabricatorConfigSchemaSpec {
         'persistence' => PhabricatorConfigTableSchema::PERSISTENCE_CACHE,
       ));
 
+    // TODO: All readers and writers for this table were removed in April
+    // 2019. Destroy this table once we're sure we won't miss it.
+
     $this->buildRawSchema(
       id(new DifferentialRevision())->getApplicationName(),
-      DifferentialRevision::TABLE_COMMIT,
+      'differential_commit',
       array(
         'revisionID' => 'id',
         'commitPHID' => 'phid',

src/applications/repository/worker/commitmessageparser/PhabricatorRepositoryCommitMessageParserWorker.php

@@ -231,13 +231,6 @@ abstract class PhabricatorRepositoryCommitMessageParserWorker
           ->addEdge($commit->getPHID(), $commit_drev, $revision->getPHID())
           ->save();
 
-        queryfx(
-          $conn_w,
-          'INSERT IGNORE INTO %T (revisionID, commitPHID) VALUES (%d, %s)',
-          DifferentialRevision::TABLE_COMMIT,
-          $revision->getID(),
-          $commit->getPHID());
-
         $should_close = !$revision->isPublished() && $should_autoclose;
         if ($should_close) {
           $type_close = DifferentialRevisionCloseTransaction::TRANSACTIONTYPE;