Bug 21651: Remove language specific sql file for notice templates related tables

Bug 21651: Remove language specific sql file for notice templates related tables

This patch removes the 3 following files for the different languages
- message_transport_types.sql
- sample_notices_message_attributes.sql
- sample_notices_message_transports.sql
They were all identical, only one version is kept in installer/data/mysql/mandatory

.txt files are removed as well

They inserted data for
- message_transport_types
- message_attributes
- message_transport_type

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>