improve: deprecate redundant ManagedInformerEventSource.getCachedValue (operator-framework#3196)

Signed-off-by: Attila Mészáros <a_meszaros@apple.com>

Author: csviri

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/event/source/informer/ManagedInformerEventSource.java

@@ -206,6 +206,10 @@ public Optional<R> get(ResourceID resourceID) {
     return res;
   }
 
+  /**
+   * @deprecated Use {@link #get(ResourceID)} instead.
+   */
+  @Deprecated(forRemoval = true)
   @SuppressWarnings("unused")
   public Optional<R> getCachedValue(ResourceID resourceID) {
     return get(resourceID);