SERVER-44041 Enable prepare_transaction_index_build.js when two phase index builds are enabled

Author: louiswilliams

jstests/replsets/prepare_transaction_index_build.js

@@ -5,11 +5,9 @@
  * writes if the prepared transaction commits after a hybrid index build commits.  The long term
  * solution to this problem is to synchronize index build commits.
  *
- * TODO(SERVER-44041): Remove two_phase_index_builds_unsupported tag.
  * @tags: [
  *     uses_transactions,
  *     uses_prepare_transaction,
- *     two_phase_index_builds_unsupported,
  * ]
  */
 (function() {
@@ -44,7 +42,6 @@ jsTestLog("Starting a background index build.");
 assert.commandWorked(testDB.runCommand({
     createIndexes: collName,
     indexes: [{key: {x: 1}, name: 'x_1'}],
-    writeConcern: {w: 2},
 }));
 
 const session = primary.startSession({causalConsistency: false});