Revert "Truncate oversize 'tx' messages before relaying/storing." - part of CVE-2013-4627 fix

This reverts commit c40a5aaaf484855a4350fd702e8e72fd21a68155.

This commit is part of CVE-2013-4627 fix, I missed this on security fixes backports that I did some days ago, sorry for forgetfulness.

Details about is here:
https://github.com/bitcoin/bitcoin/pull/2871