Subprocess(Call Activity) is created with userId null

**Describe the bug**
If a process has a sub-process(CallActivity) and if the execution before sub-process is async, sub-process is not being listed in modeler-ui. Only the parent process itself is seen at process instances tab. When I check admin-ui I can see that sub-process instance there but with Started by:(None)

**Expected behavior**
Sub-process should be started with the user of parent process

**Code**
org.flowable.engine.impl.persistence.entity.createSubprocessInstance()
in the above method userId is retrieved by calling
String authenticatedUserId = Authentication.getAuthenticatedUserId();

since the execution is async there is no authenticated user in the context and this sets startedby field as null.

**Additional context**
Flowable Version 6.5.0-SNAPSHOT