[Windows] Turn off text mode correctly in Rewriter to stop CRLF translation

I incorrectly changed the RewriteTestAction::ExecuteAction's file to binary instead of the proper RewriteIncludesAction::BeginSourceFileAction in https://reviews.llvm.org/rGbc5d4bcc2deb71ab647270c9754a83484b3d6f87. In the original commit, I actually changed RewriteIncludesAction::BeginSourceFileAction in https://reviews.llvm.org/rGfdb640ea30d416368b76b68b106deda580c6aced. This should fix the issue @aganea is facing.

Reviewed By: aganea

Differential Revision: https://reviews.llvm.org/D99837