[entropy.const] move Entropy Resources Lock path to /var/lib/entropy

This commit moves the Entropy Resources Lock from:
> /var/lib/entropy/client/database/<arch>/.using_resources
to a simpler:
> /var/lib/entropy/.using_resources

The main reason for the move is to make such path more consistent across
architectures.

lib/entropy/const.py

@@ -1101,7 +1101,7 @@ def const_configure_lock_paths():
     @return: None
     """
     etpConst['locks'] = {
-        'using_resources': os.path.join(etpConst['etpdatabaseclientdir'],
+        'using_resources': os.path.join(etpConst['entropyworkdir'],
             '.using_resources'),
     }