Migrate remaining TEXT columns to LONGTEXT

To avoid cases where mysql silently truncates json data
when it is > 2^16 bytes, migrate all remaining TEXT columns
to LONGTEXT, in a similar way to the fix for bug #1210799

Combined with the fix for bug #1215501 which limits the request
body size, we should never truncate, even if mysql is configured
such that it can happen

Fixes bug #1223029

Change-Id: Ib536cfa8e2952a5e047cd8573288cdd9fee0622c
Merge "Migrate remaining TEXT columns to LONGTEXT"