ENG-6600: Use auto-reconnect in the client lib in test apps.

For test apps that were doing reconnect on connection failure, I changed them to
use the auto-reconnect feature in the client lib.

There are a couple of test apps that reconnect to a recovered cluster, which is
not supported by the reconnect feature in the client lib due to instance ID
mismatch. Those apps are left unchanged.
Merge pull request #1517 from VoltDB/ENG-6600

ENG-6600: Use auto-reconnect in the client lib in test apps.