Reenable the TestExportSnapshot family of tests

The yarn history server can take a while to start. It is hardcoded at one minute before all is killed. On loaded servers can take this long to start. Cannot disable history server in tests nor can we configure the mini yarn cluster so it can take longer starting history server. After this addressed, and yarn history server is given more time or disabled, reenable the TestExportSnapshot* family of tests. See parent issue for details.