Some tasks don't have to run on every tenant. The task to calculate the
TSV is only done for records which were present before we added the TSV
column, and that isn't going to happen in any tenants because we added
the TSV column before adding the tenants table. Similarly, the migration
needed for existing polls isn't necessary because there weren't any
tenants before we allowed to set the starting/ending time to polls.
We aren't adding any tests for these tasks because tests for rake tasks
are slow and tests creating tenants are also slow, making the
combination of the two even slower, particularly if we add tests for
every single task we're changing. We're adding tests for the
`.run_on_each` method instead.
I was thinking of leaving these tasks empty, so in the future we could
use them again if we rename or remove more settings. But since we
haven't renamed nor removed any settings for more than seven months, and
we've only used these tasks once, I'm simply removing the tasks. It's
easy to add them back if we ever need them.
These tasks dealt with data migrations or stats generations which were
done only once, so we don't need them anymore.
New CONSUL installations don't need these tasks, and existing CONSUL
installations will execute them when upgrading one release at a time.
