Fix migration set_length_of_description_field_metering

If PostgreSQL version is less than 9.1.13 migration
set_length_of_description_field_metering fails as there is no
special 'create if not exist' expression. This change add special
function for this case.

Closes-bug: #1348138

Change-Id: Ibe4f370fe400072abd281bd2313261790335eae2
Merge "Fix migration set_length_of_description_field_metering"