SimpleDateFormat constructor takes too much time on initializing NumberingSystem

Deleted Component: formatting

While investigating another SimpleDateFormat constructor performance problem reported by #7137, I found there is another performance bottle neck introduced in ICU4J 4.2 release. The trunk version of SimpleDateFormat takes ~40% of time for initializing NumberingSystem object in the constructor.

There is a ticket for improving NumberingSystem creation performance (#6708), and NumberingSystem cache was introduced by the ticket. However, this caching is done in NumberFormat and did not resolve the performance issue in other code path (SimpleDateFormat constructor). The caching should be done in the NumberingSystem factory method rather than NumberFormat.