Bug 1879410: Add a text block in Dashboard page using TestingDataGenerator.php

Modified create_block() functionality of TestingDataGenerator.php to generate
blocks in the Dashboard page

Modified code based on review comments - moved sql query to else block, used list
instead of array and added type='dashboard' in sql query, modified dashboard
str match from preg match

Change-Id: I8880226008217b0bc3ed9b97301ad060c998d058
Signed-off-by: Aatharsh Girishwar Vijaya Sugumar <aatharshsugumar@catalyst.net.nz>
(cherry picked from commit d811cd3c)