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/container/test_core_avl.odin

@@ -20,9 +20,6 @@ test_avl :: proc(t: ^testing.T) {
 	iter := avl.iterator(&tree, avl.Direction.Forward)
 	testing.expect(t, avl.iterator_get(&iter) == nil, "empty/iterator: first node should be nil")
 
-	r := rand.create(t.seed)
-	context.random_generator = rand.default_random_generator(&r)
-
 	// Test insertion.
 	NR_INSERTS :: 32 + 1 // Ensure at least 1 collision.
 	inserted_map := make(map[int]^avl.Node(int))

tests/core/container/test_core_rbtree.odin

@@ -14,9 +14,6 @@ test_rbtree_integer :: proc(t: ^testing.T, $Key: typeid, $Value: typeid) {
 	defer mem.tracking_allocator_destroy(&track)
 	context.allocator = mem.tracking_allocator(&track)
 
-	r := rand.create(t.seed)
-	context.random_generator = rand.default_random_generator(&r)
-
 	log.infof("Testing Red-Black Tree($Key=%v,$Value=%v) using random seed %v.", type_info_of(Key), type_info_of(Value), t.seed)
 	tree: rb.Tree(Key, Value)
 	rb.init(&tree)

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 {

tests/core/slice/test_core_slice.odin

@@ -11,8 +11,7 @@ test_sort_with_indices :: proc(t: ^testing.T) {
 	test_sizes :: []int{7, 13, 347, 1031, 10111, 100003}
 
 	for test_size in test_sizes {
-		r := rand.create(t.seed)
-		context.random_generator = rand.default_random_generator(&r)
+		rand.reset(t.seed)
 
 		vals  := make([]u64, test_size)
 		r_idx := make([]int, test_size) // Reverse index
@@ -63,8 +62,7 @@ test_sort_by_indices :: proc(t: ^testing.T) {
 	test_sizes :: []int{7, 13, 347, 1031, 10111, 100003}
 
 	for test_size in test_sizes {
-		r := rand.create(t.seed)
-		context.random_generator = rand.default_random_generator(&r)
+		rand.reset(t.seed)
 
 		vals  := make([]u64, test_size)
 		r_idx := make([]int, test_size) // Reverse index