Refactor: cts: Drop Environment._seed_random()

• self["RandSeed"] isn't used anywhere.
• From the random.Random.seed() documentation: "None or no argument seeds from current time or from an operating system specific randomness source if available."
• The specific default seed source is an implementation detail that doesn't really matter.

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>