Add log message for quantization state cache eviction due to size (#2120

) (#2122)

Signed-off-by: Ryan Bogan <rbogan@amazon.com>
(cherry picked from commit ccc59b1)

Co-authored-by: Ryan Bogan <rbogan@amazon.com>

src/main/java/org/opensearch/knn/quantization/models/quantizationState/QuantizationStateCache.java

@@ -107,6 +107,11 @@ public void evict(String fieldName) {
     private void onRemoval(RemovalNotification<String, QuantizationState> removalNotification) {
         if (RemovalCause.SIZE == removalNotification.getCause()) {
             updateEvictedDueToSizeAt();
+            log.info(
+                "[KNN] Quantization state evicted from cache. Key {}, Reason: {}",
+                removalNotification.getKey(),
+                removalNotification.getCause()
+            );
         }
     }