Remove unnecessary from DDTSS_Get_Users()

This removes sorting since ddtss_match() returns already sorted array. Moreover, sorting in DDTSS_Get_Users() doesn't work because it uses operator for numeric comparison, not for string comparison. "map" does nothing, it returns array as is, so it is also removed. This removes regular expression because it is the same as prefix and all it does is slow down database query. And this removes unused variables.