Low: CTS: Fix argument handling for certain scheduler tests.

A couple date-related scheduler regression tests accept arguments.
When running all the tests in one go, the regression test grabs the
arguments out of the SchedulerTest object automatically.

If you run these tests individually (using --run), it is expected that
you will provide the command line arguments yourself. If you don't, the
tests will fail. Instead, it should default to grabbing the arguments
out of the SchedulerTest object if you don't provide any on the command
line.

Fixes T835