Remove "DifferentialGitSVNIDField" custom field in Differential

Summary: Ref T11114. This is obsolted by the narrower `DifferentialGitSVNIDCommitMessageField`.

Test Plan: Browsed around.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T11114

Differential Revision: https://secure.phabricator.com/D17075

src/applications/differential/customfield/DifferentialGitSVNIDField.php

@@ -1,45 +0,0 @@
-<?php
-
-/**
- * This field doesn't do anything, it just parses the "git-svn-id" field which
- * `git svn` inserts into commit messages so that we don't end up mangling
- * some other field.
- */
-final class DifferentialGitSVNIDField
-  extends DifferentialCustomField {
-
-  public function getFieldKey() {
-    return 'differential:git-svn-id';
-  }
-
-  public function getFieldKeyForConduit() {
-    return 'gitSVNID';
-  }
-
-  public function getFieldName() {
-    return pht('git-svn-id');
-  }
-
-  public function getFieldDescription() {
-    return pht(
-      'Parses the "%s" field which Git/SVN can inject into commit messages.',
-      'git-svn-id');
-  }
-
-  public function canDisableField() {
-    return false;
-  }
-
-  public function shouldAppearInCommitMessage() {
-    return true;
-  }
-
-  public function shouldAllowEditInCommitMessage() {
-    return false;
-  }
-
-  public function renderCommitMessageValue(array $handles) {
-    return null;
-  }
-
-}