TransactionEditor: micro-optimize the "creation finder"

Summary:
The foreach starting at old line 1305-1311 was designed to look for a specific transaction type.

When we have found that, let's stop that loop, so, we save some CPU cycles.

Test Plan:
Note that getTransactionType() has not side-effects.

Test some applications - like Pholio - that use the TransactionEditor:

- Create a new Pholio and Save
- Save it again without changes.
- Save it again with changes.

Everything still working normally.

Reviewers: O1 Blessed Committers, aklapper

Reviewed By: O1 Blessed Committers, aklapper

Subscribers: aklapper, tobiaswiese, Matthew, Cigaryno

Differential Revision: https://we.phorge.it/D25627

src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php

@@ -1307,6 +1307,7 @@ abstract class PhabricatorApplicationTransactionEditor
       foreach ($xactions as $xaction) {
         if ($xaction->getTransactionType() == $create_type) {
           $mark_as_create = true;
+          break;
         }
       }