Gather Partitioned Region clear operation performance metrics

We need to have a table which gives us an  idea how long a region clear operation takes corresponding to how large a region is.
We will also need to take measurements with persistence enabled and redundancy variations.

Please attach the numbers and other findings to this Jira and the RFC mentioned in GEODE-7665 [https://cwiki.apache.org/confluence/display/GEODE/Support+for+clear+operation+on+partitioned+region]