Use test's random generator

This removes the `create` calls when a test was only setting up a
generator, and it replaces them with `reset` when run in a loop.

tests/core/hash/test_core_hash.odin

@@ -53,8 +53,7 @@ test_xxhash_zero_streamed_random_updates :: proc(t: ^testing.T) {
 		testing.expect(t, xxh3_128_err == nil, "Problem initializing XXH3_128 state")
 
 		// XXH3_128_update
-		random_seed := rand.create(t.seed)
-		context.random_generator = rand.default_random_generator(&random_seed)
+		rand.reset(t.seed)
 		for len(b) > 0 {
 			update_size := min(len(b), rand.int_max(8192))
 			if update_size > 4096 {