GH-8699: Fix Issue of removeLockKey()

In the current code, an `IllegalStateException` might be thrown from the try block while invoking the `removeLockKeyInnerUnlink()` method, especially when caused by key expiration (resulting in `unlinkResult == false`).

This triggers the check block, which incorrectly sets the `unlinkAvailable` flag to `false`, even if the Redis server supports the unlink operation.

As a consequence, the subsequent `removeLockKeyInnerDelete()` method is invoked when it should not be.

* `IllegalStateException` should not be thrown from try block
* Add a comment and fix Checkstyle violations

**Cherry-pick to `6.1.x` & `6.0.x`**

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

@@ -476,13 +476,10 @@ public final void unlock() {
 
 		private void removeLockKey() {
 			if (RedisLockRegistry.this.unlinkAvailable) {
+				Boolean unlinkResult = null;
 				try {
-					boolean unlinkResult = removeLockKeyInnerUnlink();
-					if (!unlinkResult) {
-						throw new IllegalStateException("Lock was released in the store due to expiration. " +
-								"The integrity of data protected by this lock may have been compromised.");
-					}
-					return;
+					// Attempt to UNLINK the lock key; an exception indicates lack of UNLINK support
+					unlinkResult = removeLockKeyInnerUnlink();
 				}
 				catch (Exception ex) {
 					RedisLockRegistry.this.unlinkAvailable = false;
@@ -495,6 +492,15 @@ private void removeLockKey() {
 								"falling back to the regular DELETE command: " + ex.getMessage());
 					}
 				}
+
+				if (Boolean.TRUE.equals(unlinkResult)) {
+					// Lock key successfully unlinked
+					return;
+				}
+				else if (Boolean.FALSE.equals(unlinkResult)) {
+					throw new IllegalStateException("Lock was released in the store due to expiration. " +
+							"The integrity of data protected by this lock may have been compromised.");
+				}
 			}
 			if (!removeLockKeyInnerDelete()) {
 				throw new IllegalStateException("Lock was released in the store due to expiration. " +