Revert "Truncate encoded instance message to 255"

This reverts commit bd9c32289ff8cf1bc67c1395ad921c703aa4c489.

UTF-8 character bytes size varies from 1 to 6. If truncating a long
bytes string to 255, the last character may be cut in the middle,
so that UnicodeDecodeError will occur when converting it back to
unicode. Need to revert this code change and make a new patch.

Related-Bug: 1389102

Change-Id: Ie439cffe11d657e77397c9070a3923a61f68a678
Merge "Revert "Truncate encoded instance message to 255""