Boundary events are ignored after migration

**Describe the bug**
Hi All,
I encountered strange behavior when migrating a process to a new version with boundary events on call activities. Let’s say we have a process with one call activity. After starting it, it will stop at this call activity.
Now let’s add a timer boundary event to this call activity, and then migrate the process without mapping elements:
`def migrationBuilder = ctx.processMigrationService.createProcessInstanceMigrationBuilder();
migrationBuilder.migrateToProcessDefinition(toDefinitionId);
migrationBuilder.migrate(processInstanceId);`
The call activity is still active after process migration, but timer will never start it’s branch.
If we change timer boundary event to signal / message boundary event we will face the same issue.
Issue is also described here: https://forum.flowable.org/t/boundary-events-are-ignored-after-migration/8454

**Expected behavior**
Boundary event listeners are active, waiting for corresponding event.

**Code**
Model v1:
` Flow_01272tt Flow_01272tt Flow_109iv2i Flow_109iv2i Flow_01272tt Flow_01272tt Flow_109iv2i Flow_109iv2i `
Model v2:
` Flow_01272tt Flow_109iv2i Flow_01272tt Flow_109iv2i Flow_1c56b9v PT1M Flow_1c56b9v `

**Additional context**
flowable-spring:6.6.0
postgresql