Update split SDK to 6.0.2 to fix sync bug (#17060)

* Update split SDK to 6.0.2 to fix sync bug

* Vendor and tidy

vendor/github.com/splitio/go-toolkit/v4/sync/atomicbool.go

@@ -0,0 +1,41 @@
+package sync
+
+import (
+	"sync/atomic"
+)
+
+const (
+	falseValue = 0
+	trueValue  = 1
+)
+
+type AtomicBool struct {
+	value uint32
+}
+
+func (b *AtomicBool) Set() {
+	atomic.StoreUint32(&b.value, trueValue)
+}
+
+func (b *AtomicBool) Unset() {
+	atomic.StoreUint32(&b.value, falseValue)
+}
+
+func (b *AtomicBool) IsSet() bool {
+	return atomic.LoadUint32(&b.value) == trueValue
+}
+
+func (b *AtomicBool) TestAndSet() bool {
+	return atomic.CompareAndSwapUint32(&b.value, falseValue, trueValue)
+}
+
+func (b *AtomicBool) TestAndClear() bool {
+	return atomic.CompareAndSwapUint32(&b.value, trueValue, falseValue)
+}
+
+func NewAtomicBool(initialValue bool) *AtomicBool {
+	if initialValue {
+		return &AtomicBool{value: trueValue}
+	}
+	return &AtomicBool{}
+}