Major - P3 When working on WT-6263 to set stable timestamp in test format, rebalance starts to return ebusy because it can't do the checkpoint with stable timestamp.
/*
* Don't flush data from modified trees independent of system-wide checkpoint when either there
* is a stable timestamp set or the connection is configured to disallow such operation.
* Flushing trees can lead to files that are inconsistent on disk after a crash.
*/
if (btree->modified && !bulk && !__wt_btree_immediately_durable(session) &&
(S2C(session)->txn_global.has_stable_timestamp ||
(!F_ISSET(S2C(session), WT_CONN_FILE_CLOSE_SYNC) && !metadata)))
return (__wt_set_return(session, EBUSY));