Activation expiration can lead to a deadlock on MSSQL

[romanstrobl]

When a concurrent update occurs due to activation expiration, this situation can lead to a deadlock on MSSQL, similar to the situation described in issue #1609.

Deadlock scenario:

• UPDATE due to background expiration of an activation
• UPDATE due to expiration of an activation due to request for an activation list, activation status, activation lookup, etc.

[romanstrobl]

Another problem with concurrency during activation expirations from a background job and a service call triggered by REST a API call is that callbacks are executed twice in case of concurrent expiration of an activation.

[OliverJanstaWultra]

We couldn't reproduce this issue, but we will keep it open for a while if the issue occurs somewhere.