Fix pool counter usage

By default the pool counter allows you to lock the same key with multiple
types.  That might be useful but it isn't how Cirrus thinks. Instead, Cirrus
now scopes all keys to their types.  That means that locks for the
_elasticsearch key  using the Namespace type are independant from Search type.

Change-Id: I7586162cfb32ddbe460a25c956c845f2f4a49b0f
(cherry picked from commit b8042c6ca24ed5c02ce0d76d9dcdcc4464ac2c59)