This commit removes and now forbids all uses of
java.util.concurrent.ThreadLocalRandom across the codebase. The
underlying issue with ThreadLocalRandom is that it can not be
seeded. This means that if ThreadLocalRandom is used in production code,
then tests that cover any code path containing ThreadLocalRandom will be
prevented from being reproducible by use of ThreadLocalRandom. Instead,
using org.elasticsearch.common.random.Randomness#get will give
reproducible sources of random when running under tests and otherwise
still give an instance of ThreadLocalRandom when running as production
code.
871d1b4885