Change default filter cache to 10% and circuit breaker to 60%
The defaults we have today in our data intensive memory structures don't properly add up to properly protected from potential OOM.
The circuit breaker, today at 80%, aims at protecting from extensive field data loading. The default threshold today is too permissive and can still cause OOMs.
 The filter cache today is at 20%, and its too high when adding it to other limits we have, reduce it to 10%, which is still a big enough portion of the heap, yet provides improved safety measure.
 closes #5990
Fix StackOverflowException for long suggestion strings

Changed getFiniteStrings to use an iterative implementation instead of
recursive, so we don't use a Java stack-frame per character for each
suggestion at build & query time.