[MINOR][SQL] Remove signature from Hive thriftserver DEBUG log

### What changes were proposed in this pull request?

This PR aims to remove signature from Hive thriftserver DEBUG log.

### Why are the changes needed?

This is aligned with the upstream Apache Hive project.
- apache/hive#4887

This is also aligned with the previous Spark change.
- #43402

### Does this PR introduce _any_ user-facing change?

No, this is a debug message removal.

### How was this patch tested?

Pass the CIs and manual review (because this is a removal).

### Was this patch authored or co-authored using generative AI tooling?

No.

Closes #49752 from dongjoon-hyun/minor_debug_msg.

Authored-by: Dongjoon Hyun <dongjoon@apache.org>
Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>
(cherry picked from commit 4a33e96)
Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>

Author: dongjoon-hyun

sql/hive-thriftserver/src/main/java/org/apache/hive/service/CookieSigner.java

@@ -78,9 +78,6 @@ public String verifyAndExtract(String signedStr) {
     String rawValue = signedStr.substring(0, index);
     String currentSignature = getSignature(rawValue);
 
-    if (LOG.isDebugEnabled()) {
-      LOG.debug("Signature generated for " + rawValue + " inside verify is " + currentSignature);
-    }
     if (!MessageDigest.isEqual(originalSignature.getBytes(), currentSignature.getBytes())) {
       throw new IllegalArgumentException("Invalid sign");
     }