GetAllSubjectResources can cause dbcontext concurrency error

[knuhau]

Description

Calls to GetAllSubjectResources can cause dbcontext concurrency error

Reproduction

1. For local reproduction, set FusionCache duration on the SubjectResource cache to 1 second here
2. Call /api/v1/serviceowner/dialogs/ with a enduserId and a ServiceResource

Expected behavior

Returns dialog(s) belonging to the indicated ServiceResource and visible to the given EnduserId

Actual behavior

500: Internal Server Error
System.InvalidOperationException
A second operation was started on this context instance before a previous operation completed. This is usually caused by different threads concurrently using the same instance of DbContext. For more information on how to avoid threading issues with DbContext, see https://go.microsoft.com/fwlink/?linkid=2097913.

Additional information