shard_insert_getlasterror_w2.js should set TestData. skipCheckingUUIDsConsistentAcrossCluster

Since this test manually stops 2 nodes of a replica set before calling shardingTest.stop(), it should set the flag to indicate not to check UUID consistency.

The test is also not always testing slaveOK reads since it doesn't explicitly wait for the primary to step down after shutting down the secondaries. If it did correctly wait for the primary to step down, the UUID check would fail consistently.