tests: samples: Apps shouldn't set tick rate

Tick rate is becoming a platform tunable in the tickless world.  Some
apps were setting it due to requirements of drivers or subsystems (or
sometimes for reasons that don't make much sense), but the dependency
goes the other way around now: board/soc/arch level code is
responsible for setting tick rates that work with their devices.

A few tests still use hard-configured tick rates, as they have
baked-in assumptions (like e.g. "a tick will be longer than a
millisecond") that need to be addressed first.

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>