Sets the detachAllOnCommit setting.

DetachAllOnCommit set to false specifies that the state of persistent instances in the cache after commit is defined by the retainValues flag. With this flag set to true, during beforeCompletion all cached instances are prepared for detachment according to the fetch plan in effect at commit. Loading fields and unloading fields required by the fetch plan is done after calling the user's beforeCompletion callback. During afterCompletion, before calling the user's afterCompletion callback, all detachable persistent instances in the cache transition to detached; non-detachable persistent instances transition to transient; and detachable instances can be serialized as detached instances. Transient transactional instances are unaffected by this flag.