Gh-10446: RedisLockRegistry stopRenew is not thread safe

Fixes: #10446

Signed-off-by: PiotrDuz <[email protected]>

**Auto-cherry-pick to `6.5.x` & `6.4.x`**

Author: PiotrDuz

spring-integration-redis/src/main/java/org/springframework/integration/redis/util/RedisLockRegistry.java

@@ -601,8 +601,9 @@ protected final boolean renew(long expireAfter) {
 		}
 
 		protected final void stopRenew() {
-			if (this.renewFuture != null) {
-				this.renewFuture.cancel(true);
+			ScheduledFuture<?> renewFutureToCancel = this.renewFuture;
+			if (renewFutureToCancel != null) {
+				renewFutureToCancel.cancel(true);
 				this.renewFuture = null;
 			}
 		}