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