Allow disabling of core and jdbc statistics via configuration

From our performance testing, we are able to improve system response time by crudely eliminating runtime statistics.

Av. system response time(s) from our performance testing, each metric represents a different operation within the performance test;

With statistics enabled; 0.035s/0.245s/1.515s/0.685s/1.975s

With statistics disabled; 0.035s/0.059s/0.578s/0.278s/0.756s

We need to be able to disable statistics in JdbcStatisticsPlugin and ManagedConnectionPoolStatisticsImpl (plus anywhere else runtime statistics are generated) via a configuration option.