job_precreate_pool_get_handles() doesn't honor TROVE_SYNC flag

[carns]

Bug reported by Becky Ligon. The job_precreate_pool_get_handles() has a flags argument that should allow the caller to tell it to sync before completing. This flag is not used in any invocations in trunk because the state machines that use it count on subsequent trove operations to perform the sync. However, other potential users of this function (such as Becky's replication work) may rely on the get_handles() function to perform its own sync.

The condition that demonstrates this problem is to call job_precreate_pool_get_handles() with TROVE_SYNC and then immediately kill -9 the server. If the same call is repeated when the server is restarted, then it will give out the previous handle again rather than a new one.