Do not preload ThreadLocalRandom class.

ThreadLocalRandom.seeder field uses time in its initialization.
Preloading the class fixes initial state of ThreadLocalRandom,
which leads to the same sequence of generated numbers across
different app runs.

Bug: 234816154
Test: verified manually that TLR.current().nextInt does not return
the same sequence of numbers.

Change-Id: I80868217e02862e8d0a568ea096e22e919ec06e3