Make unsetConfiguration non-blocking

Send saving of the unsetConfiguration call to client to different thread
using ExecutorService to not block when it is called.

Signed-off-by: Tomas Slusny <slusnucky@gmail.com>

runelite-client/src/main/java/net/runelite/client/config/ConfigManager.java

@@ -313,6 +313,8 @@ public class ConfigManager
 		String oldValue = (String) properties.remove(groupName + "." + key);
 
 		if (client != null)
+		{
+			final Runnable task = () ->
 			{
 				try
 				{
@@ -322,6 +324,9 @@ public class ConfigManager
 				{
 					log.warn("unable to set configuration item", ex);
 				}
+			};
+
+			executor.execute(task);
 		}
 
 		Runnable task = () ->